The single-player campaigns in RD are a good example of what results from this kind of approach – photoshopped 2-D artwork, poorly edited and translated text, and an overall sub-par experience. This is to say nothing of AoA, which apparently fell flat on all accounts.
Obviously times have changed since I started playing RTS games but I still think the campaign is the way to get new players on board. Just make up a series of expansions set some time between 1945 and now, each campaign should be a standalone. I agree with Markenzweiback about F2P, it just isn't my sirt of thing. I'd be fine paying for a campaign pack if it came with maps and so on, just have a different setup for multiplayer. The more I think of it the more it makes sense, but like Boris Yeltsin I'm tired and emotional right now.