Also, I don't mind when someone decides to change paths with his character. Leave one guild, join another, that's how it should work.
What I really hated is that your character could become a master of everything, there were no choices or sacrifices to make.
IMO, there should be a finite amount of skill and attribute points, and when I want to increase something when I hit the limit, I have to shave the points of something else. If we stick with the thief-goes-warrior example, I might want to lower my security skill to get more points into heavy armor.
If every character looks the same in the end, there is no role play involved.
This is a decent point, but then how would you decide which and to what magnitude skills would fade? Should they fade over time or with disuse. But if they fade with disuse then realistically how can someone who hasn't fought in years still fight when they need to like in real life? Or maybe we should be able to manually un-assign them. After all no-one can be good at everything, but how does reasigning points accomplish that... I don't know how you could implement this, but I wouldn't be totally against it.
As an alternative I could, however, see them bringing back the major minor and misc skill system, because it was hard as all heck to raise misc skills in Morrowind. But even then misc skills could, and I'm sure were, maxed out... Perhaps the skill cap should be 200 instead of 100 to create a larger gap between what you excell at and what you are just okay at in addition to having Major, Minor, and Misc skills?
*Fixed because I cannot type well today.*