Its not though. Capcom have a finite number of teams and devs working on MH. They made the right choice in putting their resources into MHW and leaving Nintendo.
Or they could make another MH game for PS4/5/PC and sell another 10-15 million.
Did they though, make the right choice? On Switch there's a good chance it would have sold just as well or at least nearly as well, considering Switch's Japan dominance. But it would have cost less to make for Switch. So I wouldn't say keeping it off Switch was the right decision at all.
Or they could make another MH game for Switch and sell another 10-15 million, and have it cost less to make. So what's your point? Or they could double up and make a version for those other systems and a version for Switch and sell maybe 25 million without having to make a whole new game. Either way you cut it, Capcom isn't doing the smart thing. Seems to come down to third parties want to promote games with the highest level graphics, and they'll decide to forego more money simply for that sake. Hard to understand the business behind that, but that is what we've clearly seen for years now.