On the one hand, I agree; too many people, for reasons I can't always fathom, want to constrict the options available in the game. Not only do they want a prohibition on adding any new classes like artificer or psion, but they also often want the current class list cut by 1/2 to 2/3s of the current PHB.
That said, some concepts don't really warrant more than a subclass. Samurai, assassin, swashbuckler, and most gish builds really don't need more than a good subclass to get the essence of and the old 20-level versions of those classes were often a waste being little more than watered-down or hodgepodge mixes of current classes anyway.
I've looked a few 20 level witch classes, and the only one I really liked was Zarieth's version. I am just as happy with a sub to realize the concept as well. But I too get annoyed that D&D is one of the few games that people want things cut from rather than expanded upon.