Give me a fully developed co-op campaign in which the settings and missions are built around being tackled by several different classes at the same time. Basic battlefield grind for the assault class, but with alternate routes and objectives for a stealth/assassin class. Same level, same end, different objectives throughout.
That would interest me. This shooter that they are showing off, not so interesting.
Why not just give you the alternative routes and objectives and not limit your abilities based on class? Why not just give you the entire suite of abilities you can upgrade FREELY (not limited to class-based paths) and map access and just let you have fun figuring out how you want to tackle it the way YOU want to, using a character customized the way YOU want?