You don't have to look further than SFV and MvCI to see what only focussing on the base competitive game does to sales, and those are franchises which have absolutely enormous tournament scenes compared to Soulcalibur.
It doesn't have to be CaS, but fighting games need to remember that they're not just about fighting, they're also games.
And I mean, I have spent an hour digging my 360 out of the wardrobe, plugging it in, hooking it up to the internet, plugging in the 5 cables into the back of my tv... sorting out Microsoft's shitty email crap... then put it all away, on multiple occasions, just to be able to mess around with CaS. It's a very powerful feature for some, that's all.