I thought I would reproduce my reply to KDLadage's post on RPGnet:
KDLadage said:
So far, I would say that the biggest problem with prestige classes has been the misuse of them by players and DMs in the D&D/d20 community.
Prestige classes were never intended to be generic -- so at the most, each example if a prestige class given in the DMG or any of the various splatbooks (or campaign settings, or Dragon Magazine, or what have you) should -- at most -- be seen as a template for the creation of a Prestige class for your campaign.
While I sort of understand where you are coming from, I really have to disagree with the basic statement.
What is "generic"? Usable in all games? Under that definition, certainly, I would agree. But your statement seems to be that you should never use a prestige class unaltered. I really have to differ with that.
A lot of the ideas in the prestige classes are ideas that appear in many standard D&D games. Do your wizards congregate in guilds? If so, then mage of the arcane order may be an appropriate prestige class. Likewise fist of hextor is as easy fit to Fist of Idan in my game, and the followers of Erythnul become followers of Arimesan. Some of the greyhawk specific references get in the way, but many of the concepts are basic enough that they work in a variety of games.
I have a little "to do" list of prestige classes that I want/need to make for my world. I find that with every supplement, I can cross off a few of those classes. Some may need a nip and a tuck, but many make it into may campaign as is. The trick is that the campaign worlds uniqueness comes, in part, by the elements you have chosen to include.
Prestige classes are much like many other mechanical aspects of the game: they are elements of the world / characters. If those building blocks fit the construction of the world, then use them.
I maintain a list of appropriate prestige classes for my world, with some tweaks, alterations, or background notes to make it fit. To my pleasure, an article in the latest dragon recommends that you do just this.