While these things are true, they aren't definitive in terms of how good an actor someone is. Will himself has gone on record as saying that he's taken on certain roles in order to display and expand his range of skill and further cultivate his craft... If he were only concerned about the money and fame, he'd stick to making summer blockbusters. However, it's obvious that Will takes acting seriously. Even during the FPOBA days, when he gained more influence over the plot lines, he sought to address more serious themes and display more serious acting. I think the thing that many don't realize or are just starting to realize is that Will actually enjoys acting. He hasn't approached it as some fad or money making endeavor; he enjoys it and wants to be good at it. Anyone who approaches a craft in such a manner can't help but be a little concerned about what their peers and experts in their field think of them.
It's great to be personally content, but it's even better to be personally content while having others speak highly of what you do. I don't think Will's primary goal is to "prove people wrong." I think he genuinely cares about film and really wants to display his skill and acting abilities as well as broadening his body of work, but as competitive as he is, I fail to believe that he isn't somewhat motivated by some of the unkind words some have said about his acting skills in the past. An Oscar would go a long way in silencing a lot of people. A lot. Of. People.