I think that the big problem has always been that the Burroughs Estate has blocked most of the companies from making anything Barsoom.
The result is that many companies have been putting out "just like the real thing" knock-offs, and naturally for legal reasons they can't be just like the real thing. I've got a whole pile of the stuff, and it's cool but it's not really Barsoom. (I have the SPI John Carter of Mars game, TSR's Warriors of Mars, and the Heritage minatures rules sets. They're Mars but no longer supported.)
Somebody needs to grab this franchise and do it right. Get the Michael Whelan artwork, the Frank Frazetta artwork, make it actually look like the Mars books. Get the rights to use actual names, to stat out actual characters and creatures of Barsoom. And the rulebook and any sourcebooks need to be in color. Ideally I'd love to see miniatures, but just getting a RPG would be amazing!
I'm not sure if it should be in RQ or d20 or what system. I'm not sure that it would matter. If anyone lands the franchise and does it right, I'll throw away half my Mars collection and only keep the "real thing."