Y'know, it surprised me when I learned that so many people were so deeply butthurt about wizards in 3e. I mean, here you've got a classic "paper tiger" kind of class, who could do pretty effective things when they could do anything at all. They were not very good in a combat, since spells were prone to interruption, did crap for damage, and didn't work half the time.
It took me a while to realize that their problem wasn't that spellcasters were powerful, but that spellcasters could do things other classes couldn't, just as a function of their class. My wizard gets fly. Your fighter can't fly (unless they happen to find the right magic item). My wizard gets fireball. Your fighter can't fireball (unless they find the right magic item). My wizard gets charm. Your fighter can't charm...etc.
Spellcasters also changed the rules of the game. SR came into play because of spells. Save-or-die hurts your big cinematic combat, and neither result is desirable. Exploration spells gave DMs headaches thinking of ways to thwart teleporting and flight. Divination spells gave DMs headaches thinking of ways to thwart knowledge gained with a simple class ability. Climaxes were ruined all over the place, or DMs bit the bullet of a magical arms race. They forced the DM's hand.
So instead of addressing that issue directly, 4e just said, "Nope, we're not going to do it," turned everything into a combat spell, and shoehorned the leftovers into rituals, which were kind of obviously an afterthought.
And so people proclaimed it "fixed," since spellcasters now only did the exact same thing that everyone else did, just with different names, making it easy to predict a party's capability, and making sure a DM had to do next-to-nothing to ensure their adventure was climactic.
But, it wasn't "fixed" it was just nixed. And people who enjoyed -- or even who didn't mind -- the aspect of the game that let them do things like charm and teleport and divine the future were rather understandably annoyed that the designers had thought so little of the way that they had been having fun for years that they just deleted it. And so they left to support a company that has continued to support their playstyle.
And they've supported that company to the point that it has become the reigning #1 tabletop RPG company.
Which at least means, to my mind, that if it is unbalanced, that it is to such a small degree that people who are buying RPG books really don't give a flying flumph, making those earlier criticisms seem overblown, and the WotC response to them seem draconian.
"OH GOD, MY CHILDREN ARE MILDLY DUSTY!"
WotC: "Guess we're going to have to rip off their skin so they can never get dusty again!"
Audience A: "Yay! No more dusty children ever! That dust was SO annoying! Now I can take my kid to fancy society functions!"
Audience B: "Um...gross and no. What? You don't need to do that."
Paizo: "Well, all I've got is this muddy rag, but maybe it'll help? And maybe you'd like a muddy kid better than a child with no skin?"
Audience A: "Bah! That child is still very dirty! It is gross, how can you take it?"
Audience B: "Yeah, no, we'll take that...perhaps we can find a way to clean them off later that doesn't rip off their skin?"
