You raise an interesting issue. I think, perhaps, that there should be "basic" monsters that are very quick and easy to use and there should be "setpiece" monsters that are more complicated. An orc vs. an orc chieftain, perhaps. Whereas the orc might might have only standard melee/ranged attacks, the orc chieftain might have several special abilities. That way the majority of fights with "basic" monsters can go quickly and easily, but if you want to throw in the "setpiece" monster to distinguish them, you can.