Sorry, but this is a self-fulfilling prophecy.
There is no reason why the Wizard couldn't be designed in such a way that there is a super-simple option. One cantrip at will and 2-3 known spells (with a short list of suggestions for beginners so that they don't need to scour the complete list) would make for a decent 1st level Wizard.
Almost all people I've seen play D&D for the first time wanted to do some magic, and were often told "Sorry you can't be the cool character because it's too difficult for you, play a Fighter for a couple of years then maybe". Many of them didn't get that far, but I bet some didn't because they got the message they couldn't play what they wanted.
Exactly.
I know that MMO analogies are unpopular and often taken to be insulting, but I really, TRULY do think that MMOs have something that tabletop games--and D&D in particular--could learn from. In most games--say, FFXIV or GW2, or even WoW--there are classes with dirt-simple mechanics, minimal need to worry about "rotation" or "uptime/downtime" or whatever, and some of them are "martial." There are also classes with complex chains, linked skills, dependency on combos or an involved rotation...
and some of them are also martial.
D&D, for whatever reason, has devoutly held onto this strange conception that "magic = complicated, melee = simple"--or, rather, melee =
simplistic. It's become ingrained, practically a symbol of pride for some gamers, that Fighters are for noobs, Wizards are for "experienced" players, and that concept generalizes to other similar classes (even 13A is guilty of it--the Fighter, Paladin, and Barbarian are all lower-complexity, even if you pull out all the stops, than a typical Cleric or Wizard). But not everyone who is new wants to swing a sword; not everyone who likes playing Fighters (or even "Fighter-types") likes minimal-complexity classes; not everyone who likes casting spells prefers high-complexity classes.
But if they--WotC, Pelgrane,
anybody--really care about attracting sales and "growing" rather than "maintaining," this seems like THE biggest sacred cow we have yet to slay. Some versions of D&D have been better and others worse, and the D&D Next playtest even paid lip service to the idea...only to completely and totally abandon it later.
So I guess that's something I'd add to my answer, or rather that I would give in answer to the slightly different question, "What
isn't the Fighter class to you?"
The Fighter class
isn't defined by a particular level of complexity. It isn't confined to being complex OR simple, and instead covers a wide swathe of options.
Speaking, of course, about D&D and not other systems. Dungeon World, for example, the classes are intended to be small and self-contained, but (relatively) easy to create (among other useful attributes that make DW a different beast from D&D).