We're talking about a player having to be smart to play a wizard, which I disagree with.
.
Ah- my bad.
Still, I have no problem with the Wiz having a higher intrinsic complexity than other PCs. Here's a suggestion- if your "low-IQ" players are having difficulty running them...
HELP THEM OUT!
(I say this having handheld a lot of noobs, kids and utter idiots* through the early stages of roleplaying a particular game.)
"Dude, a braniac like Boomadore wouldn't wade into combat with his dagger, he'd launch that lightning bolt at that BBEG."
"Don't you think that Boomadore's Grease spell would be appropriate at this particular junction?"
"Meteor Swarm----
NOW!"
or even
"Ehhh...Summon Care Bear is a suboptimal spell, and it really doesn't fit your character's style. How about a protection or attack spell from that level?"
Eventually, even the dumbest RPGer can find his stride as a spellcaster, maybe even an arcane archetype he can manage quite well. Perhaps he'd shine as a "Tim" and keep launching fire spells.
* In particular, I remember a HERO player who could never figure out how many die he was supposed to roll...for the same attack, and a 3.5 player who couldn't figure out attack rolls. In both cases, the groups were happy to have the players along because- mechanics ineptitude aside- they contributed to the fun of the gaming sessions with their role play.