My take on the issue :
http://www.gamesas.com/topic/1522152-why-make-it-harder-for-us-to-tell-our-own-story/
For one thing, for the X th time, stop bashing someone because he has a different opinion than yours. Someone can be skeptic or hatefull of a product without any kind of hard feeling (or any kind of feeling at all) for those who love it. Please, do the same toward them. Otherwise, it is just mean, arbitrary, gratuitous and useless.
About the characters backstory, there is an amount of things that is under its control and an amount of things that were set upon him by life itself, just in real life. You don't choose your skin color or were you were born, those things happened before any involvement from yourself. Let's call those things background. But the background isn't really who you are. Then, there is an amount of thing that aren't your decisions, but aren't the decisions of others either. Having a low HQ, a weak constitution, some mental disorders etc... Those things are your nature, which is different than your background. Then, you have your personnality, which is who you are deep inside. Then you make choices and you have motives that lead to those choices. Then, you have your evolution, that is your life between your birth and the present, which is a mix of all of those things, including your nature, your choices, and your motives. At last, there are outside events that happened to you, without any control from yourself, that don't depend on who you are, but isn't either related to your background.
In Fo1-Fo2-FoNV, to generalize a bit, the only things that are already defined are parts of your background (you were born in Vault 13/Arroyo), and an outside event that force you to leave. You didn't decide to go for the water chip, or the GECK, but were chosen by your people for doing that task, not because you are worthy, but expendable, or randomly chosen, or because Hakunin plants say so. Hell, you can be a complete moron with a weak constitution, unable to fight a rat, and still be chosen. The other members of your settlements might even lampshade this by considering the wrong person was picked. The choice of sending you doesn't depend on who you are at all. Then, you have indeed made a choice, but the only choice was to accept the task and leave your hometown. But if you didn't leave the hometown, you wouldn't explore the gameworld. So it isn't hard to accept that your character would you the same thing as the guy who bothered to buy the game. Explore the gameworld is mandatory for both of you or there would be no game. Other than that, there is one other forced choice in Fo2, destroying the Enclave, but there is several possible motives. Destroying the Enclave because you hate them, saving your village, or just self-survival, as they want to kill everyone, including you. The courrier also chose to become a courrier, but we don't know anything past that. He might enjoy the job, or just doing that occasionnally amongs thousand of other jobs, he might owe ton of money etc...
Other than that, everything is up to you. You can decide the rest of your background, you can decide your nature, you can decide your personality, you decide your choices and motives, you can decide your evolution, you can decide who to side with in main/side quests, (and if you want to meet/kill Benny, find the chip, learn about them, or ignore them) you can decide your behavior, if you want to kill everyone, kill no one, be diplomat, be violent, be stealthy, have great intelligence, be a complete moron, be strong, be weak etc... Only things decided for you are a bit of background and one outside event that kick you in the gameworld.
In Fo3, they are already in a middle ground. You have more background elements forced upon you (lost your mother, were born outside, raised by a doctor father in a vault, expelled at 19, be loved by your father), but those are background elements. You can theorically choose your nature, personnality, some of your evolution, some motives, choices etc... You might say that somehow, you are forced to love your father, but you can choose to semi-antagonize him or at least disrespect him. You are free to antagonize or love Butch and Amata. The problem is that no matter if you keep mistreating your father and Amata, they will keep loving and helping you (imagine that the first person that comes to help you agains't her own father is the one you bullied for 19 years). Which gives the impression that the game refuse to aknowledge your agency. Not matter your choice, what happens next is what the develloppers chosen instead of what you chose. You can be a very kind and forgetfull Fo3 apologist and consider that those Vault people love for people they spent all their life with can never be broken. If that so, why so many of them try to kill you ? Let's be kind and consider that you have an input in your vault life. Then you are kicked from the vault, but not because who you are, but because what another character (your dad) did, and the overseer mistrust of him and his relatives.
After you leave it, it only goes downhill. No matter the nature, personality, motives, evolution and choices you try to provide to your character, the devellopper will always force him to make some choice (which, being forced, annihiliate the concept of choice) that can and probably will contradict all the character building you made. No matter what you decided for your character, he will escape your control and follow the develloppers orders, by looking for dad, helping him, joining the brotherhood, looking for the geck, and helping activate project purity. Not only your characters will have to do those things to finish the game (if you add Broken Steel, he wouldn't even be able to actually finish the game), but the others characters will also lose their agency by having a predetermined behavior instead the one they should have after your own action. If you killed thousands of BOS members, Lyons should never consider you as an hero, for instance.
So, IMO, Fo3 mostly managed to give you some input in the beginning (but still removing a lot of your agency compared with Fo1-Fo2-FoNV), pretend to leave you some agency afterward, but completly blow up the illusion when you are following the main quest. Which is, at best, a mixed bag. At worst, a complete denial of your agency.
About the blank state, it mostly fits to FoT. You can define some part of your nature (stats), and tiny part of your personnality (choosing to do optionnal objectives and how), and one (very committing) to join the BOS and follow its order. Everything else is a blank state, IMO, not because you don't have forced personnality/motive/nature/background/etc, but contrary to Fo1-Fo2-FoNV, there is not enough options in the game to allow you to choose how you will fill the blank and how the NPC will respond to it. With Fo1-Fo2-FoNV almost everything in the gameworld, allow you to make choices, define who you really are (despite the partial background and the single forced event) and the gameworld is reactive enough to react to it, providing the much needed consequences.
Which makes us pretty much worried, is not only the controversial way of handling those choices (of lack of) in Fallout 3, but also all the things that seem to be forced upon us, that go well beyond background and one single forced event. The tone of your voice, your heterosixuality, your marriage, your child, how you decorated your house, how you talk to your wife, buying the robot butler and choosing its programming. All of those things involve some develloppers decisions overriding your own, about your character's nature, personnality, behavior, evolution, motives and choices, with cover all the factors mentioned above. Of course, we cannot know to what extend the regression will occur, as it is only the beginning of the game, but so many devellopers choices overriding our own in just a few minutes is indeed extremely worrying.
Also, considering that the dev stated a few times that they wanted to give the player freedom, they seem about to fail that promise, by removing from the player several aspects of a freedom he already had in almost every other titles of the series, a freedom that was amongs the very things that made that series worth of praises in the first place. No matter if we love or hate that trend, a part of the player freedom to control its characters was removed. The remaining question is how much of this freedom we will still have at the end.
Once again, i am explaining an evolution and why some of us are worried. You don't have to be worried if you think that this freedom is unecessary.