It doesn't surprise me that Mexico and China are not taking to XIII as well. Current information tells me its had lots of bugs and glitches, so that might be it. For tournament players, 02UM is still close to what they know so there's less room for error. The USA is more interested in flash, and I dunno how to explain why its taking off decently in Japanese arcades, but a console release is necessary with good netcode for it to work here. But I dunno, the look and style of the game is not something overly appealing to Americans really. I don't think even with strong netcode or balanced gameplay that would change things. Proper marketing could do it, but SNKP can't afford the marketing necessary to do it. Ignition cannot either (if they even wanna continue doing business with SNKP). A juggernaut company like EA would be able to market it and make it sell well for sure, but its doubtful SNKP would approach an American producer to do so, and even more doubtful they'd agree to it. Really, sad but true, hand-drawn 2D sprites are going the way of the Dodo and have been for quite some time. They're gonna need to mimic the style of SSFIV or MvC3 to really make a game succeed, and outsourcing to some company that doesn't know a thing (Guys behind Sen) isn't an answer. They also need to not worry about marketing towards current SNK tournament players or fanboys and focus on drawing in people (like what SSFIV did) and the tournament players will naturally follow along anyway if it gets enough attention. I also would rather see them revive some older IPs and not care so heavily about KoF...but thats a story for another thread.
tl;dr - SNKP put everything into something that was mostly a waste of time and should focus on a 3D game with a 2D plane, and probably use heavy marketing in the West to increase sales as well as strong netcode. Not that I won't buy whatever they come out with anyway, and I love 2D sprites more...just see them dying out. This article kinda sums up why:
http://www.eventhubs.com/news/2011/mar/04/svensson-sprite-based-fighters-extremely-difficult-sell/