>>2
It's not because of sales
The game got okay sales actually, they weren't thunderous but the profits would've been enough to fund another sequel. And the amount of sales it got were really amazing too considering the game was released near the end of the PS1's OFFICIAL life span. The reason why there's no sequel is because Inafune got distracted with other Mega Man shit and DR plus LP. However he did make the DR/LP engine not just for this gen's games, but for MML3. Too bad he bid his time too much and Capcom got too greedy, if he had been bold about it we would have gotten MML3.
Last gens AAA publishers/stock holders were happy with at least 2 million sales, now if a game doesn't make 10 mil+ it's deemed a failure.