Are PrCs supposed to be this powerful?

[Keld Denar]

Being strictly better than not getting a prestige class has made every decent build include them, which is the exact opposite of their original intent.

There are plenty of decent builds that don't use any PrCs. Swift Hunter and Daring Outlaw are both considered very good damage builds, and neither of them use ANY PrCs. Straight Warblade, Swordsage, Crusader, Dragonfire Adept, Factotum, Totemist, Druid, and a few other base classes are often as strong or stronger than many PrC alternatives.

Also, not all power is creepy. Complete Arcane contains some crap like Iot7V, Sublime Chord, Fatespinner, and the lauded Mindbender dip, which are WAY stronger than most of the PrCs in CChampion, CMage, or CScoundrel, all of which came later.

Just sayin...your generalizations are kinda...not right.