First, I'd say it depends upon what kind of game you want to run. If, for example, you intend to run a game simulating an author's novel in which there were characters of vast disparity of power, 4Ed's design would do a spectacularly bad job of emulating that setting.
Setting aside the questionable desireability of having /PCs/ of different power-levels (the extreme ends could be NPCs - side kicks and deus ex machina types), if balance isn't desired a balanced system like 4e can be used simply by assigning resources (like levels) asymmetrically. Getting imbalance out of a balanced system is simplicity itself and you have a good idea of just how great the disparity will be, as well.
sometimes too much balance is bad. It can lead to stagnation and stalemates in gameplay.
Lack of choice can do that, certainly, but that's also a form of imbalance.
And one of the consistent complaints levied at 4Ed is its combats can be a boring grind.
There are many consistent complaints leveled at 4e that are simply unfounded. The foundation for this one is the earliest adventures written for the game. Monsters initially had higher defenses and more hps and lower damage figures - and the early published adventures continued the 3e practice of using significantly overlevelled monsters to represent 'bosses,' rather than using solos. MM2 adjusted defenses, and MM3 increased damage figures. So combats became faster. Another factor with the early reports was relatively low level, 1st level characters have only 1 encounter and 1 daily, and otherwise depend on their at-wills. Any combat over 3 rounds necessarily includes at-wills, so very long combats can get repetitive (unless the DM has placed terrain-based powers for the PCs to utilize, or the players try to improvise, of course). 4e combats can still be long, in rounds, but they aren't often 'boring' - that is, characters all remain involved and are rarely reduced to flailing away with at-wills.
Compared to the issues other editions had with low-level combat and lack of in-combat options for particular classes, even with what tendency towards the 'grind' it may still have, 4e comes out well ahead.
As I've played the game over the past few years I've seen it happen in person. There is something in 4Ed's strict adherence to balance that has made combat less fun for many players.
Again, balance does not cause the grind. Imbalance in early monster and adventure design did.
Part of it (and only part of it- I don't have all the remedies) is that one roll per attack sequence that predominates in 4Ed. This happens in other games, too, but 4Ed's version just seems to drag for some reason.
That reason is called 'confirmation bias.' The number of rolls needed to resolve 4e powers isn't out of line, at all. Earlier eds were much more generous with multiple attacks, and rolling damage once and saving throws for each creature in a fireball for half damage is the same number of rolls as to hit each target, with 1/2 damage on a miss, and rolling damage once.
Simply put, combat lacks sparkle.
Now /that's/ subjective.
And, I'm not going to argue it. If 4e combat doesn't 'sparkle' for you, and some other game does, by all means, play the sparkly one.
And it didn't have to be like this. There are other ways to balance games that are out there. HERO is my game of choice, for instance. Despite combats that can be as long as or longer than 4Ed combats, I've never felt a HERO combat was "grindy."
There's a lot of variation among Hero characters, because they are so customizeable, but, in general, they have a small number of powers that tend to skate close to whatever the campaign maximums are. You're generally making mechanically very similar attacks each phase. And, yes, Hero combats take a /long/ time, especially for the amount of time they represent.
The genius of Hero is just how effects-based it is. It really goes all the way, power names are just mechanical place-holders, and a given power can have any remotely appropriate 'special effect.' It can manage just about any concept you can think of. Playing a character that's so close to your concept of it is exciting, in itself. No ed of D&D can touch Hero in that regard - including 4e, though it did take a halting step in that direction by divorcing flavor text and mechanics. But, then, Hero is one of the best systems of all time.
Or at least, it has been at points in its history (I'm not so familiar with the latest version). My one major objection to Hero is the open-ended skill list, which as I put it "creates incompetence" (one way this manifests is the point-inflation of skill-heavy packages: when 'professional skills' were introduced way back in Champions! II, 2points in "Lawyer" made you a competent member of that profession, able to earn a living at it - 20 years later, in Hero 5th, being a Lawyer is something like a 60-100pt package deal). 3e suffers from the same issue to a lesser degree, with skills like Craft and Perform that each represent an endless variety of possible skills you could define into being, and thus make everyone who doesn't invest ranks in them bad at. The 5e playtest also shows signs of the same malady.
