Its just that my personal experience as a gamer since 1977 simply doesn't jibe with that assertion- besides me and my buddy, the majority of the guys & gals I've played D&D with in the past 32 years have been perfectly capable of self-restraint in combat.
I have no doubt that lots of people are
capable of it.
Where my questioning comes in is, how many people would have
chosen it?
Obviously, there's no way for either of us to answer that, since we're getting into the realm of hypotheticals and guesses on other people's motivations. But my own experience--and my understanding of the
average person--is that people prefer to be able to decide for themselves on this sort of thing.
So a class that lets you
choose whether you want to play a conservative, "I only act every few rounds" type is going to have a wider appeal than a class that
forces you to play that type.
And no, you can't just say "Well, they shouldn't play a wizard then." Wizards are too much of a fantasy archetype to restrict them to what is--IME, and apparently judging by WotC's research--a relative minority playstyle.
My first 4E character was a rogue. And there were times where I spent several rounds just moving, to position myself for the perfect sneak attack, even though it might've been more mathematically sound for me to spend those rounds attacking even without SA damage. And I enjoyed doing it.
But I enjoyed it because I
chose to do it. If I'd been
forced, if (for whatever reason) I was incapable of contributing meaningfully without first maneuvering for position, I'd never have played the class.
I played wizards, a
lot, in 2E and 3E. And I enjoyed the experience. But I enjoyed it
in spite of the fact that there were times I just couldn't meaningfully contribute (especially at low levels), not
because of that fact.
I have to wonder if certain design decisions were made because of assumptions about the predominant playstyle within the game that may not be justified.
I have no access to WotC's research, and I certainly won't claim that their design decisions are infallible. But I do know that they
have such research, and I trust that,
for the most part, they have a strong sense of what the majority of their market is looking for.