I don't think that maple is the real problem, even though it breaks differently than white ash does.
If you look at game bats from before the 1950s, the amount of use that they took was simply amazing. After about 1960, you start to see the majority that have a few ball marks and nothing else except for a crack in the handle. The bats of the last 50 years simply do not last.
I think the reason is the circumference of the handle. In the 1950s, players started switching to lighter bats that were extremely barrel-heavy so that they could generate more bat speed with less initial force needed. The result was bats with very thin handles that break much more easily than the old ones.
I'm fairly certain that if there were a minimum handle circumference, we wouldn't be seeing anywhere near the amount of bat breakage from either ash OR maple.