Firstly, it is an official OCR album - it has it's own OCR supported project thread, it's hosting plenty of big names and everything. Secondly, it is now moving at a noticeably decent pace. See, it may have started in 2009, but it suffered a freeze that lasted the entirety of 2010. Between that and Bahamut joining the military it's suffered a few hickups, but it's now moving along quite well.
Just saying, is all. BTW, Bahamut and I are holding on to more than a few pretty epic tracks from that project, so be sure to stay tuned to when we can actually release them (as a preview or otherwise).
Also, for the record Bionic Commando also has an official OCR album in the works (it is also official), as DjMokram's pointed out. Again, older and less known, but it's also moving along, little by little.
Kyle seems to have covered WA well enough... and unlike the other two projects, there is a definite date for the release of that one. December 20th, the anniversary of the release of WA. Look forward to it.
Anything MM related should be covered by the Grand Robot Master Remix Battles that Darkesword hosts every year. Look it up - the first two were excellent, and there's a new competition brewing now as we speak. If that doesn't satisfy your need for Megaman (even those past 1-3) then I can't help you...
As for the others... yeah, I agree they're underrepresented here. Moar Legend of Mana, especially.