i think Morroblivion was mostly banned because of a misunderstanding regarding exactly what it was. it's been a really long time since i last bothered to look at it but i'm pretty sure the only resources included were fan-made recreations of Morrowind weapons/armor, and everything else was either Oblivion vanilla or converted from a required Morrowind install.
Fallout3.esm loads in New Vegas without a hitch, apart from a ton of missing/incorrect refs and bugs. i tried it with the actual .bsas too but it crashed as soon as the Fallout 3 title slide came up (which in retrospect might have been because of .ini incompatibilities, which i think would be trivial to sort out). i'm sure with some fiddling and a compatibility patch it would work near-flawlessly - copy over and rename the Fallout 3 .bsas, copy over the music, edit the .ini to include the newly-renamed Fallout 3 .bsas, rig up a starting cell to present a DO YOU WANT TO PLAY NEW VEGAS OR FALLOUT 3? prompt (kind of like Throne of Bhaal~), bada bing.
actually hell i don't think you'd even need a Morroblivion-esque conversion program - just a patch and a small guide telling people what to do.
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I could care less if bethesda approves it, I mean Moroblivion is still available off it's official site.
yeah but it's also completely dead. imagine the progress that could've been made if Bethesda had authorized it.