Regardless of quality the main issue I see with Tokyo Mirage is that it has a very, very limited audience. It lacks a strong voice or identity.
It carries a lot of baggage from the crossover standpoint, it doesn't appeal to SMT fans in terms of tone, designs or setting, doesn't have enough Fire Emblem at a glance and even the game itself only touches those elements at an extremely shallow level, one can't easily tell which Performa is supposed to represent X FE character, and outside of those it doesn't really appeal to the taste of other series from Atlus, so it is kind of screwed in that sense for fans of these series.
At that point the appeal comes from seeing the Atlus and/or Nintendo trademark and trust that for the average consumer.
The idol stuff I don't think helps it a lot, pretty much fighting an uphill battle against other idol brands and games that are more accessible and the like, TMS situation being much worse with its lackluster marketing.
And the name is pretty terrible, just the cherry on top of its appeal issues.
