Unit sizes in mp battles are now fixes since patch 8

Patch 8 introduced an undocumented but welcomed fix for the unit size in multiplayer battles

here is my inital visualization about this issue, CA accepted some time ago.
https://www.youtube.com/watch?v=X2Ab6IxEjJ0

http://forums.totalwar.com/showthrea...hosted-battles

Hooray!

I was going to say it is probably intentional for reasons you mentioned in your video but then, you can choose a unit size for a MP campaign just fine.