If that designer was hired because of a business decision to move away from the OGL and his pitch was to try to bash the OGL version of the game into obscurity and make a radically different and incompatible game that everyone would have to switch to, it's less than a playstyle problem. It's a business problem. They wanted to convince people to pay a subscription fee for a game that had been partially available for free and to buy a new edition while the old one was still warm on the press. They created reasons for people to spend money on their products. Addressing gameplay issues is not likely to have been a major consideration in any of this.
The designer I obliquely mentionned was Mike Mearls. The design leads for 4E were all in-house guys from the 3E era; Bruce Cordell has been working on D&D since the TSR days. Everything I read in the ramp-up to 4E was to the effect that they knew, from consumer-survey data and their own internal testing, that certain elements of 3E were out of whack because of specific changes from 1/2E to 3E (the way saves worked vs. the DC of spells, monster hp ballooning due to Con modifiers multiplied by hit dice, etc.).
Of course, there was a marketing strategy behind the new edition; no company worth their salt would launch a new product without making a pitch to consumers, but there were reasons for the switchover from 3rd to 4th edition beyond "let's make some cash". To paraphrase Andy Collins (I believe) "when you design to circumvent the game's problematic features, it's time to change the game."
Also, to say that 3.5 was still "warm on the press" might be misrepresenting things a bit: the last big rules addition to 3E was, undoubtedly, the Tome of Battle (which was inspired by the 4E design process), and before that, maybe the Tome of Magic (?). Otherwise, not that many substantive supplements came out in 2006-2007 (pretty much the same output we're seeing now, at the tail-end of 4E). So while material was being published, I wouldn't say it was all top of the line game supplements.
I could post a many-layered argument for why 4E did what it did, but it wouldn't change anybody's mind about it, but it's not related to this particular discussion. I'll just say that "balance" was and, according to a recent article by the lead designer of the new iteration of D&D, is a concern for the design team. Heck, it was a problem Gary Gygax himself struggled with.
Not to put too fine a point on it, but if you're playing a game you ostensibly like and you're not having fun, one which continues to dominate the rpg market (albeit partially under a different brand name), I don't get how you can conclude that it's the game's fault.
It's the game's fault when, by the core rules, the best rogue is a wizard/sorcerer, the best melee combattant is a spellcaster, when ANY role in a party can be filled by a spellcaster, and when those same spellcasters can negate entire encounters by bypassing the game's established conflict/situation resolution mechanics.
No one's saying it's perfect, but those extremely negative experiences suggest that you either needed to change what game you were playing or how you were playing it. I'm guessing you did at least one of those.
I did change it. I can play any type of D&D game I want with 4th edition. It does everything every past edition could do, and the guy playing a fighter doesn't feel like a moron for having picked a non-caster class. Is it a perfect game? Hell no! But it's a lot more honest, fair and clear than 3rd edition ever was (1st and 2nd had a sort of in-game balancing system where you were never meant to play non-casters past 10th level, but it was kind of obfuscated). Again, I run bog-standard, basic adventures based largely on published materials and DM advice included in the books. To say that my experiences are due to my "playstyle", basically puts in doubt my reading comprehension or my understanding of D&D as a tabletop fantasy role-playing game. As a guy who's been playing this game for close to 20 years, I very much disagree.
Edit: mis-attributed the quote to Andy Collins, it was James Wyatt, and the quote went: "When the game gets to the point where we know tge holes and pitfalls in the rules well enough that we constrain our design in order to avoid them, it's time for a new set of rules."
