But this is the thing, the fighter is not equal to Hercules, Conan or even Duck Dodgers!
But he IS equal to Hercules. Maybe not at first level. But if you take a 21st level Fighter, they are able to do almost everything Hercules can. Even at first level though, he's more akin to Aragorn at the beginning of the first book than he is a peasant who just picked up a sword like 1st level fighters were in 1e/2e.
The wizard has been demoted; not everyone else upgraded. As for the player wanting to outshine his or her peers - I can buy that to a point for certain players but to tar all wizard players with this same broad brush is incorrect. What is wrong with wizards doing wizardly things? Are we so scared of save or suck that everything now has to be in terms of attrition and grinding away?
Everyone got an upgrade. They just got a smaller upgrade than the Wizard got a downgrade. The average 1st level fighter can take on a bunch of lowly goblins and possible a goblin "leader"(read, non-minion. In 3e it would have been a bunch of normal goblins with a couple level 1-3 classed goblins) or two by himself. This group would kill him for sure in any other edition of D&D purely due to lucky rolls.
I don't believe it has to do with being much more powerful than everyone else for everyone. For a lot of people, it's just the ability to wield EXTREME power. I understand that. I miss it sometimes myself. But I understand, intellectually that the kind of power they used to have is no good for a game where I play with 4-6 other people.
What people want out of a Wizard is the ability to wave their hands and have all their enemies turn to stone or into frogs. No way to stop it, because their enemies are not Wizards...and only those who have magic can protect against it.
They want the ability to jump out a window at any time and fly to their destination in no time flat. They want the ability to wave their hand and turn all of their allies invisible for as long as they want.
And people were willing to compromise with the 1e-3e system. They couldn't fly WHENEVER they wanted, only as often as they had the spells prepared. They needed to be high enough level to cast those spells...but they'd get there eventually if they just waited long enough.
But even with all those restrictions in place, it is a far cry from being a 10th level Fighter to being a 10th level Wizard. The Fighter(without magic items) can....use a sword well. The same Wizard is flying, turning invisible, throwing fireballs that do more damage than the sword does to 8 enemies at the same time with no attack roll, while having skin that reflects all blows, force armor, and a force shield. All of which makes the Wizard even tougher than the Fighter is. And if he gets into trouble, he can instantly teleport anywhere he wants in the world.
The Wizard can also use spells to detect traps, trigger them remotely, walk through walls...and any number of a thousand other things.
The next effect is that it is pretty easy to feel useless when you are the one playing the Fighter and to have your fun ruined because of the "anything you can do, I can do better" effect of the Wizard.
From the DM side, it's also difficult to plan adventures around that kind of power. Unless you absolutely don't care where your adventures head, you're always playing a balancing act of "carefully lead the PCs where you want them to go without letting them realize you are leading them." That is easily destroyed when the PCs have hundreds of abilities at their disposal that you might not even expect. I've seen a game destroyed and a DM get really annoyed simply by a well prepared 2e spellcaster.
