IMHO, the reason why T:V failed is two-fold...
2. The current Tribes (1 and 2) Community.
So many T1/T2 gamers trashed the game so badly in all of the forums that anyone who came out looking to see what the game might be like would be scared off. You all know who you are, simply go back through so many of the threads to see the flamers.
So anyone out in game-buying land who decided to do as Adam suggested "suggestion is to not buy on day one. Try the demos, read the reviews, educate yourself on our games (before you buy)" would have been put off by the whiners in the forums.
Even though T:V was different (than T1/T2), and there were a number of things that should have been completed, corrected, or added, to bring it in line with the Tribes franchise, ultimately it was the T1-T2-Trashing people in the community that killed the game and its sales. Had the sales been good, even if the game had quirks, then it was foreseeable that patches and addons could have been eventually released (gee, just like T2 and many other games, you lamers). I'm sure most of the T1-T2-Trashers will admit that the original release of T2 was ok but that many of them are using the later-released addons and mods. T:V was killed coming out of the gate. Sure, we can say that IG/VUG should not have put in the SP mode and concentrated on the MP, but should-woulda-coulda doesn't cover the entire problem with this game's sales.
Many of the posts by the T1-T2-Trashers was so "boo-hoo" that they were pointless and senseless wimpering and whining, but unfortunately it most likely had a big hand in killing the sales. I know that even myself, who enjoys T:V immensely, was discouraged over so many of the posts.
And I don't believe that the box art had much to do with anything.
Had IG flushed-out the MP game fully, and had the community not undeservedly trashed the game so badly, then perhaps T:V would have survived.
DGUnreal