I upload to 3 different sites just now. There's about 14 different versions archived on filetrip even more in the shared folder on 4Shared.
Most people download from filetrip, about 55%. About 40% from WUpload and the other 5% from 4Shared. Most of the downloads are referred from this thread too. I haven't really bothered before, but lately I've been quite interested in the stats.
The main reason I started using WUpload is because they provide stats on the countries people are downloading from etc. It's pretty amazing that people from every corner of the globe are using it. Maybe I'm just a bit sad. lol
My point is that WUpload isn't the only option and I'm not sure that adding mediafire to the list of mirrors would really benefit anyone.
I used to use multiupload.com, which let me upload to about 9 different sites at once, but hardly anyone used those links, even though they're popular sites like filesonic, megaupload, zshare etc.
I fully agree with what you're saying, but filetrip is the best option to avoid that I think, rather than using mediafire.