What?
Noooooo

First off, there is already a unit cap, so how are you going to control the little units? What if you wanted to do that with a bunch of units? Increasing the unit cap will only cause the player and AI to use more full units.

How will you control it? I don't understand your idea. Are you talking about it being a separate formation? Or are you talking about physically splitting the unit? As a separate formation, what would be the purpose of it? If your whole unit simply spreads out, its the same as it was before, only looser. Again, what purpose would that serve?