Some of my own thoughts...
1) More rules to remember - If you start considering apocrypha - things like the survival guides and the like, I'm not sure that there are more rules now than there used to be. What rules there are are now far more consistant, as others have mentioned. And, as P-cat has mentioned, when all else fails, you can simply set a DC and go.
2) Being a bad guy more - I note that, if you're following the stated intent of prestige classes, going through them is in itself campaign development. Prestige classes are suppose dto be a "world building tool". If you aren't finding them to be such, perhaps you should rethink how you are using them.
3) Creating NPCs is an administrative burden - for one, it does not have to be. There's computer support to remove much of the the burden, and as others have mentioned, creating less-fully-fleshed NPCs is now easier, rather than more difficult. Also, while there may be more burden, there's also greater flexibility and opportunity. It takes longer, but your NPCs can now be more interesting.
5) Game worlds with less support - I note that comparing current official game world support with late-2e game world support isn't appropriate. Game worlds build up over time. 2e had a decade of world development, and 3e has had a couple of years.
6) Quality modules - I'd argue that actually there were relatively few "quality" modules in the first place.
And as with game worlds, there's the time to consider.
7)Rapid advancement - rate of advencement is entirely in the DM's hands. The DMG does a good job of outlining how to control advancement speed. If you're group goes up in level too fast, give out fewer XP.
As for other points that have been raised - I personally find combats are faster in 3e than in 2e, and faster than combat in many other game systems.
As for levelling up being "a nightmare"... I'm sorry to say that I find that just a bit silly. It isn't like you get so many skill points that keeping track of them is difficult. I mean, a top end rogue gets... 12? Players find allocating a dozen lousy points to be "a nightmare"? I just don't grok that.
1) More rules to remember - If you start considering apocrypha - things like the survival guides and the like, I'm not sure that there are more rules now than there used to be. What rules there are are now far more consistant, as others have mentioned. And, as P-cat has mentioned, when all else fails, you can simply set a DC and go.
2) Being a bad guy more - I note that, if you're following the stated intent of prestige classes, going through them is in itself campaign development. Prestige classes are suppose dto be a "world building tool". If you aren't finding them to be such, perhaps you should rethink how you are using them.
3) Creating NPCs is an administrative burden - for one, it does not have to be. There's computer support to remove much of the the burden, and as others have mentioned, creating less-fully-fleshed NPCs is now easier, rather than more difficult. Also, while there may be more burden, there's also greater flexibility and opportunity. It takes longer, but your NPCs can now be more interesting.
5) Game worlds with less support - I note that comparing current official game world support with late-2e game world support isn't appropriate. Game worlds build up over time. 2e had a decade of world development, and 3e has had a couple of years.
6) Quality modules - I'd argue that actually there were relatively few "quality" modules in the first place.

7)Rapid advancement - rate of advencement is entirely in the DM's hands. The DMG does a good job of outlining how to control advancement speed. If you're group goes up in level too fast, give out fewer XP.
As for other points that have been raised - I personally find combats are faster in 3e than in 2e, and faster than combat in many other game systems.
As for levelling up being "a nightmare"... I'm sorry to say that I find that just a bit silly. It isn't like you get so many skill points that keeping track of them is difficult. I mean, a top end rogue gets... 12? Players find allocating a dozen lousy points to be "a nightmare"? I just don't grok that.