I think that is easier said than done. They would either have to create new characters with more powers and defenses to fill in gaps, or use the GM Code on all of the game enemies for use in the MA... and I don't know exactly how either of those would work in practice. Neither, seems all that easy to implement.
You might wanna add some comments to my suggestion that I posted in the suggestions forum. http://boards.cityofheroes.com/showflat....=2#Post13685598
But I doubt they will ever completely remove level restrictions. The lower end enemies don't really have the powers available for them to put up a fight against level 50s, it'd be leaving the game wide open for more exploits that they'll just have to nerf.
Is there some reason that the Devs hold onto this antiquated system? If I want to make level 50 Vahzlok, I should be able to.
The level restrictions just block more options and story ideas from being implimented.
So, my suggestion is to remove ALL level ranges from all NPC villain groups. They should all be 1-54.