I think cRPG should be a fun game.
Situations such as these :
Satisfaction comes from conering a 2h with 2 hoplites and taking it in turns to stab in into a stun lock till death.
Are unfun. The guy fighting alone can't do anything (that is, how skilled he is has no influence), and the other two are just taking turns poking at him, which doesn't require much effort either.
Fighting in groups require a lot less muscle memory, that's for sure. And it's quite nice. But combat in MnB is also
a lot about creativity (and alas, how to stifle that of your opponent). Combat in groups is just poking at someone when you think you have an opening. There are no tricks, and there are a lot of "automatic win" situations (like a long spear + great maul combo).
Imagine we push the concept of "teamplay should win" to the extreme : if 2v1 were always lost by the solo guy, the game would be more realistic but still ultra boring. Or at least not an action game anymore.
Don't get me wrong, teamplay is great and fun, but it shouldn't be an "I win" button or hinder the skill aspect of this game in any way.