Fun should take priority, and I think it usually does. It’s just that in popular multiplayer games people usually find the optimum play style and then only do that, which can make the game quite boring and repetitive. One of the most viable ways to counteract that is to balance it so other play styles become more popular and make the game a bit more varied.

Another option can be to add some randomness to some mechanics so which play style is best isn’t as obvious or changes more frequently.