Classes are an illusion.
There are people and tools. People pick the tools that are most useful within a certain context. Overtime this creates popular combinations of tools.
The combinations that are not "naturally" (modeled, labeled, supposedly such and such) useful in a given situation or many situations should not be functionally distorted to perform equally as well as the proper tools.
They will only be distorted to mimic the correct tools functionally and lose their original utility.
When a situation rolls around in which the generally non-useful combinations are actually useful, the distortions imposed upon them will make them ineffective, thus creating a poverty of effective means to accomplish some goal.
In cRPG, the functionality of different items, weapons, and armor will be be reduced to a bland homogeneity, so that any combination can be equally effective under the average environmental conditions, ie. a small, slightly hilly village (or similarly contoured landscape) with about 50 teammates and 50 enemies. Included in this environment is the gold/xp economy and relevant leveling decisions. Also included is the average players skill, ping, and goals within the game (to get kills, gain gold, help teammates, be a goofball, etc.)
Weapons that excel in such conditions naturally will be nerfed, weapons that do no not will be buffed.
When the environment changes enough (new maps, larger maps, larger battles, smaller battles, different player attitudes) the "balance" will crack, crumble, and dissolve.
This is why "perfect" balance is futile given the diversity and complexity of variables within cRPG as well as its potential for a vast number of different environmental conditions. Strategus is an example of a way that the developers have made the environment even more diverse.
The game will be balanced so long as the environment, in which the combinations of tools (under the control of players) interact, is kept stagnant.Players concerned about balance will avoid the non-average battles, where the balance has broken down and certain combination are more effective than others (The duel server, for instance). It's rational to do so.