I have problems with the premise that 4th is complex and previous editions of D&D are simple. It makes 4th ed sound like the Kama sutra!
I just dont think it that complicated a system. I have seen people with little gaming experience understand and play it quite quickly. It alienated (too) many play styles, to be sure, they changed too many archetypes (like druids etc) and some players found it hard to accept the high fantasy assumptions of it, but the underlying mechanics and structure are pretty simple and uniform. 4th ed is just a different kind of simplicity.
I agree that 4e is ridiculously easy to teach. I've done it myself.
However, I'm talking about character build options here. A 4e fighter isn't horribly complex, but it certainly looks that way when compared to a 1e fighter. Hence, start with the 1e fighter and build up to the 4e fighter.
Even the 4e wizard, with four spells of varying frequency, is more complex than the 1e wizard with one daily spell.
It isn't that 4e is complex. It's that, at least from the perspective of character building, 1e characters are very simple. You have plenty of choices to make when building a 4e character, whereas you rarely do with a 1e character.
It's much easier to add options (choices) to a simple (non-choice) frame, than it is to deconstruct something into something more simple. They've already stated that the fighter will have the option to gain powers instead of simple numerical bonuses, so clearly the 4e fighter is in the works.