I've entered this thread way to late but still wanted to throw in my 2 cents. Something recently happened that addressed this same question. There is some mobile game coming out that is supposedly the "pokemon" mmo we have all dreamed about. Besides the fact that it's on mobile there's one HUGE thing wrong with it. It's simply -not- pokemon. If it turns out the be the second coming it's not going to matter because, again, it's not pokemon. I would speculate a crappy official pokemon MMO would garner 100% more attention than this other MMO, (whos name I cant even be bothered to look up because I don't -care- that much). Brand name attachment is arguably the most important aspect of... well anything really. It can make or break a franchise because of the massive fanbase large brands have. Here's a few more examples of brands and their power.
Dungeons and Dragons- the most relevant RPG in our space. Now I'm not starting edition wars but even I acknowledge the fact that 4e did poorly because it simply didn't "feel" like D&D enough. I'd wager that the system released under any other name would have massive share of the market at this point. I obviously don't have any data to back that up, but man even to this day when I talk to friends they proclaim how much they hate 4e because it felt too "video gamey". Which is the most annoying response ever, and clearly showed they didn't follow up on the game after PHB3 and beyond came out. Point here is that I can easily imagine the D&D brand was 4e's greatest enemy.
Okami/Legend of Zelda- Okami is probably the best zelda game you never played, it was fantastic and won't even get a fraction of a percentage of the LOZ fanbase.
Final Fantasy- Same deal with the D&D 4e fiasco. Final fantasy XIII was hyped beyond belief because it was the next final fantasy. Turned out the game is almost universally hated. Many time I hear "It was a decent rpg but a terrible final fantasy". Another issue is Final Fantasy vs Dragon Warrior/Quest. Here in America DQ can't garner the attention that Final Fantasy has, despite it being a fantastic franchise.
Most MMO's fit here when compared to WOW.
So yeah, to me brand is probably the most important aspect of ANY game. I made a post in the "General RPG" second about The Strange. The Strage IMO needs to get infinitely more publicity because of the solid game that it is but I know it'll never happen because of the big brands out there. It'll never even TOUCH the D&D / Paizo market share. In fact there are a LOT of games like this that deserve more than what they are getting. Eh, this is way longer than I initially intentioned, I'll bow out now.