Absolutely not. There isn’t even one consistent “Hero” character in the Dragon Quest franchise and the Luminary’s only major appearance in a well selling Dragon Quest game is 11, for obvious reason, which sold best in Japan. Saying that the Luminary is bigger than Mega Man the character just because of the size of Dragon Quest is like saying that John Price is bigger than Kirby just because of how huge Call of Duty is.
I said Hero, not Luminary.
There are four Heroes, Eleven, Erdrick, Solo, and Eight.
Erdrick, the most iconic Hero, is definitely at least as iconic as Mega Man and even on par with Cloud as a mascot.
Four Heroes represents Dragon Quest as a whole, and to even imply that Dragon Quest is a niche franchise outside of Japan is ludicrous.
To put that into perspective, the next three franchises that have sold LESS than Dragon Quest are Tomb Raider, Halo, and Just Dance!
Even if it's super ****in' duper popular in Japan, it's still a juggernaut worldwide.
Dragon Quest is absolutely not a niche franchise.