Also, traditional 'Vancian' casting isn't hard to understand, IME. I'm saying this as a DM who has introduced a fair few players to 3e, over several years. Sure, YMMV, and I respect that. But, what you're saying doesn't necessarily apply beyond your own experiences. Or maybe, not very far. *shrug*
It's not hard to understand. It is, however, hard to master and very unintuitive.
Hard to master is obvious. Planning for what kinds of things you're going to see is not something a newbie can do. But reactively choosing from a relatively short list? If you have 2 brain cells to rub together, you can pull that off almost as well as a genius.
Sorceror: Zero learning curve, pretty easy to master
Wizard: Not bad at low levels, learning curve as the number of spells available scales logarithmically better than number of spell slots... gets tough. And there's a lot of non-linearity in matching your spells to your assumptions of what you'll face that day.
If you're not a particularly great DM, you're going to see the newbie wizard sort of get confused a couple levels in while the sorceror continues to fry things and decide the sorceror is more powerful than the wizard. If, like most games, you never reach the high levels, the wizard never gets the chance to show the benefits of his better feat selection and overall versatility.
Unintuitive is also obvious, and since you've introduced many people to 3e, I'm surprised you're not familiar with it. You don't see magic types in most literature able to do something only once or twice a day unless it's really hard to do. And they seem able to do simple things constantly. You say you've never met a new player who was confused by Vancian magic. On the other hand, I've never met a new player who
wasn't confused by the entire concept.
Somewhere inbetween us, reality probably lies.
I've rarely seen anyone have trouble figuring out
how to do it, but I don't remember ever introducing an adult to the game who didn't wonder
why it would work like that.
Man... heavy duty case of deja vu. I think I remember typing almost this exact post back when 3e was newish, and some of us were wishing they had just thrown out Vancian then.