While working on a mod for the game I've determined the one thing besides the ability to rename units is we need a brigade level we raise in game similar to a division. I know the basic unit is a brigade with regiments as elements, but hear me out.
A brigade command level in game could be raised by selecting two or more single element units and brigade them together. No need for a commander with ratings like 1 stars and up. An added bonus would be flavor names could be used just to say there is a commander, but that wouldn't be prioritity.
I'm not suggesting all the scenarios be redone to do away with brigade units you recruit, but it would give the average player the ability to group together those singleton units currently in the game if they so choose. The regular US army units come to mind. Instead of assigning several of them to a division you could brigade them for a more realistic command structure.
The big benefit though would be to modders. I'd love to have regiments be the basic recruiting level, but without the ability to brigade them in game it wouldn't work right. It would allow players and scenerio designers to more accurately form historical brigades consisting of units from several states without having to define units of every possible major combination.
That would be major. But another thing that would be nice in the meantime with us having to define the brigades we want would be a page2 button on the recruitment screen so that more than 40 unit types for each category could be active at a time.