I think the plenitude of character builds arises in the following way. Suppose you want to play a character who is predominantly a warrior. You focus on leveling up skills like One-Handed Weapon, Shield, Smithing, Armour. Now, there are presumably going to be a whole lot of warrior characters which focus on these skills. But the differences arise with (i) the perks, and (ii) "minor" skills. One warrior might focus on maces, rather than swords or axes.
Okay - I'm going to jump in right there, just because this is a thing I've considered, and regarding which I've come to a conclusion. Much has been made of the differing perks for different weapons, but I'm willing to go on record right now with a prediction that, when boiled down to their basics, every weapon is going to get the same basic perks, with only minor differences.
I predict that, if laid out in a spreadsheet, we're going to find that every weapon receives essentially the exact same perks in the exact same order. Undoubtedly they will be called different things, and as far as damage goes, they'll work in somewhat different ways - the critical damage perk for swords and the bleed-out perk for axes, for instance. These will probably serve to distinguish the weapons a bit (which is certainly a good thing), but at heart, those are just two variations on "do more damage." And I predict that that's the way all the perks are going to work for melee weapons. The advancement up each weapon tree, however it's precisely set up, is going to be exactly the same. If the first perk for one weapon is simply a "use it effectively" perk, then that's going to be the first perk for every weapon. If the third perk for one weapon is a "swing it faster" perk, then that's going to be the third perk for every weapon.
I could well be wrong, but I'm confident enough that that will be the case that I'll go on record right now predicting it.
A different warrior might be more offensive and take all weapon perks, but take less armour/shield perks. Furthermore, one warrior might also dabble in healing magic and alchemy; a different warrior might be decent at archery and speechcraft. And so on.
Yes, and this is where I think the perks could shine better, though I'm wary here of a couple of other things. First - for your first example, the warrior who invests less in armor and more in weapon skill (my favorite form of warrior, by the bye), I'm concerned that, with the lack of attributes and with everything rolled into the three derived attributes, there isn't going to be any way to provide that character with the advantages he should have. Again, that's my favorite type of warrior, and I can attest that the single most important thing that that character needs, and the greatest advantage he has, beyond weapon skill, is speed. He has to be able to get in and out of melee range quickly and easily, because he can't afford to get hit, but in past games, with movement speed tied to encumbrance, he was guaranteed a speed advantage, and had an opportunity to work on it and gain even more. So in past games, it was self-fulfilling - the thing he needed most was speed and the most immediate advantage to not wearing armor is increased speed. Without a speed attribute and with the, I believe, very real possibility that speed is going to be fixed, how will that character be able to gain the movement speed he really needs in order to move in and out of range effectively? And without that additional movement speed, what point is there to wearing less armor at all?
To the other examples - the warrior who dabbles in magic or archery - I'm concerned by the almost palpable hostility I've seen to generalist characters. It's been stated, too many times for my comfort, that, effectively, generalist characters are going to be gimped. Not simply that it might be a bit tougher path to follow, but that they simply will not be able to compete. At least that's the impression I've gotten. If that holds, then dabbling in other fields is simply going to be suicide, and we're back to just climbing the specialist trees.
In general terms, while I agree that the system aims to encourage specialisation, I don't think it follows that the game will funnel players down only a handful of character builds. (I'm not sure if you meant to suggest this, but it's one way of reading what you posted, and it raises something worth discussing). Rather, I think the game will encourage specialisation by encouraging you to pick only a small handful of skills, even if those skills crosscut traditional character builds. You might still have an enjoyable and playable character who focuses on One-Handed, Enchanting, Alteration, Sneak, and Smithing.
That is indeed pretty much what I intended to say, and I remain concerned. To expand on what I just said, I don't get the impression that the game is going to reward "crosscutting traditional character builds" at all. I get the distinct impression that it's going to punish them. That, as far as "jack of all trades" builds go, the focus is clearly on "master of none." NONE. Zero. Zip. You're screwed if you even try so don't dare even try.
Now - it's entirely possible that that impression is a result of Beth going out of their way to ensure that we all understand that they're trying to prevent the inevitability of a master of all trades uber character, and that in conveying that, they've just gone a bit too far in the opposite direction with their rhetoric. However, it's also possible that they've gone a bit too far in the opposite direction with the actual game. We'll of course see, but I remain concerned.
Seem to have drifted away from my original point here though, which was simply that 50/280 is actually a pretty sizeable chunk - just a bit less than 20% - and that while mathematically, there are a staggering number of ways to arrange 50 choices out of 280 options, with the way that perks are certainly going to be ordered and interrelated - with many of the perks serving only as upgrades to lesser ones, many having to serve general roles to take the place of attributes (presuming that in fact happens) and the need to provide a progression of perks for all the skills and all the archetypal "classes," it seems to me that the number of ways in which those 50 perks might be arranged could well be uncomfortably low - that, to look at it from the opposite direction, if one were to decide on a particular sort of "class," then go through the entire list of perks, eliminating the ones that clearly aren't a part of that "class," one will end up with a remaining set of perks a bit too close to a total of 50 to provide much room for actual variation.
So, to go all the way back to the original topic and put an end to this wall of text - I'm not too concerned that 50 perks will be too few to choose, but I am concerned that 280 will be too few to choose
from.