Heroes were cool, I just wish maps didn't require to grind neutral mooks in the forest for xp. Concept of an elite unit gaining powers by participating in battles is pretty alrite for a skrimish based RTS. Also I doubt hero units were invented by wc3, they were already in warlords battlecry games
Starcraft had heroes.
Myths had veterans and pretty much all units were named.
The only thing WC3 brought to the table was 3D calarts.
Warcraft's heroes were all about introducing persistence to the genre, which is not the case with Starcraft, therefore the heroes there perform a significantly different function. Not sure about Myth. If you look at the early W3 design promises, persistence in general was supposed to play the major part, persistent heroes, persistent world where you choose missions instead of the classical linear compartmentalized RTS mission structure, etc. Most of that was scrapped obviously. Still, the heroes in wc3 have their moments, I particularly like how they played around with progression in Frozen Throne, where they inverted it, i.e. Arthas becoming weaker with missions completed.