User blog comment:Master Sima Yi/Assassinews 19-03-'14 – Two Assassin's Creeds for 2014?: Unity and Comet/@comment-5174994-20140612183407/@comment-3046679-20140612185845

What I mean is, you give co-op the option of having outfit pieces with ultimate stats, everyone will use them once they have them. Poof, no more customization, everyone will use the same things.

In single player this is not an issue. Although I didn't know you could play the co-op missions by yourself, then my point is invalid.