I agree with Rev here. uniform identification could be a great way to make up for the lack of a mini-map and dorito spotting.
As for the idea of customization as a whole. I’d say minimal is better, but still have variety. With WWI there were so many groups of different countries and their subsequent colonies, fighting in this conflict. I’m not asking for the ability to put a spray or something on my helmet or change my uniform color to maroon or barbie pink (and while having female soldiers is alright. It was still very much a male dominated career. So at best I’d say it would be subjected to the area of use. Russian’s seemed to care very little about who went to fight.)
But I’d say let’s take a bit of both worlds. Let’s have the ability to say…have a squad choose what country they are coming from. With the Allies we have France, England, America. And their colonies of India and Africa. With the Central Powers there is of Course Germany, Austria-Hungry, Bulgaria and the Ottoman Empire. Each with distinct uniforms and style. It would give the game map better flare. Instead of just having Team A vs. Team B. It’s truly the forces of one versus the other. And I think that would give it so much more of a personal and unique feel then just changing what my character wears.