Personally the space between 2000 - 2008 did have some good games. Capcom vs SNK 2, King of Fighters 2002, Tekken 5 DR, and Samurai Shodown 5 SP (to name a few) were all titles that were highly loved in the fighting community. The problem is the mainstream market was so bored with what was already there and more interested in the newer genres like first person shooter and the problem with the 2D fighting game graphics had not really updated since Street Fighter III and went backwards after that really hurt the industry.
The online fighting community was growing by leaps and bounds with older titles that fans went back to when their local arcades dried up and they never really got a chance to play anybody. SFIII3rd, CVS2, SSFIIT, KOF '02, '98 got more attention cause people could now play each other worldwide. Even though the online was mostly crap in the beginning. Capcom noticed a perfect storm coming. They had the foresight to release Street Fighter IV with characters everybody knew with promised new 2.5 HD graphics that the casual gamer wanted to see. This all caused the explosion. Not SFIV suddenly coming out and everybody swooned cause of SFIV.
I also agree that compared to other games the backgrounds in XIII are less involved but comparing EVO '09 where SFIV Finals was Daigo vs Wong. Repetitive Ha Do Kens vs Balrog's charges was not really entertaining for the casual gamer. Evo '12 the KOF XIII finals Mad_KOF vs. B.A.L.A. was MASSIVELY entertaining. It had the big combos yes, but Mad_KOF did not really use combos as heavily as B.A.L.A. Any person I ever talked to about that fight found it a blast to watch, and it caused a surge in popularity for XIII immediately after.
KOF XIII is insanely entertaining watching high level fights because of the suspense. Anything can go off in a moments notice. It's been proven that the insane combos are not the only thing that entertains the fans. To me it's a good thing you never see the fighters in XIII stagnant. It's keeps the crowd on their toes rather then relaxing when a defensive match breaks out in other games and characters look for openings. XIII gives many mechanics to make your own openings EX jumps, roll evasions, running, CD attacks are all there to make sure the game progresses faster then most games keeping the spectator more engaged.
Just an FYI the fighting game system doomed the online. It's too sensitive to allow any kind of lag. No matter what they could do it was a losing battle to make a decent online for that game. Blame it on making the arcade game 1st then worrying about online.
Last just remember that Playmore is a small company. from what we hear they are working on something new, but before KOF XIII they were close to bankruptcy. For them to make new content for a game that is 2d which takes a hell of a lot more time then Capcom's 2.5D let alone having a lot less workers to work with and less funds is massively harder then when Capcom churns out new content right away. New outfits are easy on a 3d model. on 2D not so much. What I thought they could do was put in XII stages and music along with older titles music as DLC but it never happened.
Those are my critiques. Mostly though I found it entertaining. Thanks for sharing.