There's still vast oceans of balance problems with classes (Warlocks are not as good at striking as rangers or rogues, forex, especially right out in PHB1).
Meh, there's nothing like the gulfs in class balance of prior eds. A powergamed warlock might not quite match the DPR of a powergamed Ranger, but they're both perfectly fine in normal play. Warlocks were one of those classes that really captured the imagination of players, but then failed to deliver mechanically on those heightened expectations.
There's still a lot of contention about the power level of spellcasters and warriors, but very little of it has to do with some sort of "I AM NO LONGER GOD GGRRRR" childish spite, and much of it has to do with much subtler things like suspension of disbelief and flow of play, which are not balance problems.
Very little of it /admits/ to the childish spite, of course. But, when you use 'verisimilitude' or 'supsension of disbelief' or 'flow of play' as a rationale to take away one class's toys, so your favorite class feels 'distinct and different' again, it just might start to look a little spiteful.
It's really not even 'childish,' it's a legitimate simulationist issue. You're simulating fantasy, in fantasy, magic does wild, amazing things. If any schmuck with a sharppened bit of metal and chain-link jumpsuit can do wild, amazing things, too, then magic isn't magic, and you're not simulating fantasy.
You may be playing a 'balanced' RPG, but you aren't simulating fantasy anymore.
Essentials seems like an attempt to start rolling that (balance between casters and non-casters) back...
How so?
Well, to see the hater PoV, you really have to embrace the 'slippery slope' fallacy in a big way. I mean, we're talking, tinfoil hat, second gunman on the grassy gnoll, inside job, false-flag attack type conspiracy theory here, but, if you want to understand where it's coming from...
First off, be aware that the goal of the Evil Conspiracy is to restore the 3.x and earlier status quo of casters rule, fighters drool to 4e.
Secondly, be aware that like all good Evil Conspiracies, it is vast in reach, subtle in action, cunningly concealed, and malevolently patient.
Thirdly, ... oh, I think you get the ideea...
So, the slippery slope goes like this:
First 'they' (the Conspiracy, stay with me) put out Essentials, which has 1) old-fashioned 'drooling' fighters who just hit things (and similar conceptual downgrades for other martial classes), 2) capable option-rich casters, and 3) a palpable surge of power creep to make even the crappier E-classes competative.
Next 'they' continue to put out 'support' (new builds, feats, powers, etc, etc, etc) for all the new Essentials builds. Because the caster builds are compatible, that translates into support for the parent classes, so Wizards, Clerics, all the non-Martial types, continue to get new shiny goodies to edge up their power, interest, and effectiveness as the game continues to evolve. However, because there is little such compatibility for the martial types, the support for the E-type martial classes doesn't pass through to the older, builds - with their 'suspension of disbelief'-shattering dailies.
Inevitably, over time, the old martial builds which had parity with the caster classes when they first arrived, fall behind the power-inflation curve and get left behind. Once they're far enough back that the new Essentials builds are the only viable martial options, those, too, can be allowed to languish, while spells and prayers and whatnot become ever more powerful and varied.
And, finally, perhaps enshrined with the release of a 4.5 or 5e, the fine old status-quo is restored. Purged of class balance, D&D retruns proudly to the "weird wizard show" that Gygax warned you about back in the 70s.
Why? Follow the money! (...over to Paizo, where Pathfinder is doing so well...) OK, so it's not a lot of money, but when Hasbro has the Men in Black holding your future children hostage on Pluto until you bring in more revenue, you take what you can get.
I hope you have found this 'manifesto' informative and entertaining.