I believe the lack of voiced dialog (excluding Talking Heads) allowed for more conversation options and made each Fallout 1/2 character feel more "human" and easy to sympathize with. Which certainly gave you less incentive to blow their heads off.
Perhaps it's just more bias here but I think Fallout 1/2's pixellated gore was much more tasteful. It was ridiculously obscene (firing an MP5 in burst mode at point blank and having the guy's entire upper body blown off) but so awesome. Maybe I'm just used to other shooters, so in Fallout 3 the gibs don't feel as distinguished.
In games like these we're certainly limited by our choices of interaction with the NPCs and what we can say. For instance, in Morrowind/Oblivion, I sometimes feel as if a high-ranking thief would not get stalled by the almighty dialog box when arrested by a guard. He'd punch him in the face and high-tail it out of the city, not stand by and make small talk about how he's going to repent his crimes.
If you ask me, Fallout 1 handled these interactions far better - dialog outcomes seemed far less predictable. In Fallout 2, almost every NPC (especially in hostile areas such as New Reno) had a dialog option in their conversation that was just screaming to the player,
"you svck! I want to die! Please attack me now!" :nope:
Totally agree here.
In terms of violence, the originals are much more brutal. I don't find that having an arm or leg blowing off and flying in the air with a 10mm bullet shot from a pistol to be brutal. Not at all. Not only it is ridiculous, but it's more comical. While in the originals, the preset death animations were much more realistic and disgusting to watch, along with the sound effects that came with it. Blowing up the left part of someone's hip and hearing him screaming the hell out while he's dropping on the floor was not a pleasant sight to see. Or seeing a kid getting cut in half because he was mistakenly caught in a firefight with a Plasma Rifle was also not pleasant.
I find Fallout 3's violence to be bland, really, since the NPC does not react before dying. His body just gets the Havok physics activated and his corpse goes flying in the air with no reaction. (Not everyone dies from getting his arm blown off. Hearing them scream would be much better)
And as for dialogue, well.. Fallout 3 has always been pretty bad in the Speech options.
You are forced to use guns in the main quest to finish it, "unless you use a companion as a bodyguard" like one of the Devs said in an interview I barely remember...but companions end up dying anyways and you are forced to use a weapon one day or the other.
Playing through Fallout 1 as a Speech, Barter and Unarmed person was one of the most enjoyable gaming experiences I had with the game. I never resorted to my unarmed combat for the main quests, but I did use them for some of the side quests when I wanted to get my hands bloody.