The only reason why the MLB has a good app is because they can capture the thin slice of revenue teams miss out on from out-of-market fans with that app; there's generally not enough of those fans to drive a per-team standalone subscription service (although the MLB does offer one, it's not price-competitive with the full league option), so the league does it as a whole.
Are you willing to pay $300/year+ for MLBtv?
Given how many people I know who pay $80+ a month for cable only for sports, I guarantee you'd get a lot of takers for a "stream any game, any time, anywhere, $350/yr" plan for any of several major sports, including baseball.
For every game? Absolutely. Sign me up.
For me to get my local teams and the games on ESPN I have to subscribe to a mid-level cable package which costs something like $1000 / year. To get the Peacock games, it's another $5 / month.
When I was in Hawaii I couldn't watch any of the west coast teams - Mariners, Angels, Giants, Dodgers, A's, or Padres because they were the local teams.
And don't even get me started on the "it's easier to be a fan of a team far away than your local one" that is so common now because of all the restrictions.
Why won't they sell me a tier in their app where I can see all the games? I don't mind paying more.