From the various game design analysis videos I've watched, the recurring point that gets made is that as far as balance goes, it's less important to have everything be equally powerful as it is to have everything be equally interesting. So where games go wrong is either having everything be levelled off to the point where there's nothing really interesting about any class or have things bee so wildly imbalanced that there's one obviouslly superior choice that makes all or most other choices less interesting as a result. A situation where players end up going, "sure I could go with this choice, but I could be going with the other, obviously optimal choice and have more options and do cooler stuff."
