I disagree that VF sucks, it is one of the best fighting game series around and consistently has better reviews than guilty gear.
I also disagree that interestingness correlate with lack of balance. take the comments on Shoryuken.com about MK vs. DC and all of the lack on balance in that game, is it interesting NO. VF isn't interesting to 2D people because most are used to the very fast gameplay of 2D games, so VF is the antithesis of that, hence the usual 2D vs. 3D comments back in the day. Also, for casuals, VF simply is dull, while take a look at the trailers of MvC3 with all the energy blast, the colors, the light shows, the wolverine, spidermans, hulk, chun li, ryu and other interesting people and tell me what do you think they will chose. Sales isn't everything though, take a look at the millions MK5, 6, 7 and even the vs. DC did and compare them to Tekken 4, 5, 5r, 6 and Virtua fighter 4, evo, 5, 360 version of 5.
Street fighter sold well because it was released to a mature platform and on platforms at the same time. It also was prepped by Soul Calibur 4 a half year before, and HD remix a few months before. Virtua Figher on the other hand was released literally 3 months into the $600 PS3's lifespan. Also, it is street fighter, it is the mario bros of fighting game. I'm not sure if fighting games were in a slump not because STreet Fighter wasn't being released. For example, people got tired of Street Fighter 2 version 36 (joking)after a while. And No one cares about fighting game stories as a reason to not include fighters in your game, hence the idiotic decision capcom made to not include popular fighters in Street Fighter 3. Seth Killian and Ono and other executives always mentioned time and time again that they've learned their lesson from Street Fighter III.
Also I remember asking something on VF.com about why did they have Akira's knee input kick and guard with release of guard within 1 frame. That kind of stuff just turns casuals away, and this is bad for a game that already has problems attracting casuals due to its barrier to entry, the perceived difficultness of it, the perceived stiffness of it, plus the lack of flash and interesting characters and storyline to make the characters interesting doesn't help as I mentioned above. They would often respond either A. We hardcore people like the challenge, or B. We don't mess up on it that much, we can do it 100% of the time or close to it, just practive more.
Also There is a huge lack of advertising and marketing on Sega's part. A problem they often displayed in the Genesis and Saturn Days, and continue to display ( I still love valkyria chronicles and like no one knows about it). You know who else has this problem, Nokia in the US. I have an n900 and had a n97, but in the US you can't sell unlock phones at 600 bucks and think it will sell. you have to get in bed with a carrier or two and you have to market it, think of all the (an)droid and iphone commercials. Now think of all the 0 top of the line nokia phone commercials. Get the drift.
With that said and back to topic, Fighters should strive to be balance, and striving to be balance and making all same fighters are two completely different things. Super Street Fighter IV actually did a descent job balancing. Capcom still stiffed the non original 17 arcade characters, and a few bad people remained bad in super and I don't forgive them for that, but in the tournaments, you have a group of many viable characters and that is pretty good when you have 35 characters. Blazblue in the half a year patch should slightly tweak the top 2 or 3 down, improvely greatly on rachel, tsubaki and tager (will a fighting game ever give big guys respect and make them top tier (zangief got nerfed hard, though Vangief had a good run at Evo)) and maybe slightly tweak the middle and we'll be good.
