Whoa, I better sneak this in before the thread gets closed.
There's a difference between the "out of game" loop and the "in game" loop. To me, it doesn't really matter how complicated character creation is - so long as it doesn't bog down the inner game loop, which is combat. When you've got all these modifiers and stacking/not stacking rules, and keeping track of durations of spell effects, and all this other crap, it can really bog down.
But having a nicely defined skill list and feat selection largely don't affect the in-game loop. Sure, it might make players take a little longer to decide on their action, but I think it does add a lot to the game.
I run, what I consider, to be an "old school" kind of game, but I've managed to do that within the 3.5 ruleset. Specifically, I've found the E6 ruleset, which I think accomplishes this very nicely, and very easily.
Furthermore, a few simple houserules, and the ability to "handwave" a lot of crap can really speed up play.
Lastly, I think "old school" is as much a feeling as it is a mechanic.