This, more than any other recent change, really goes to show exactly how tight the parental hand on the purse strings really is.
In a lot of ways Hasbro is making smart choices about managing the Magic brand. Someone up there who's looking at how to bring the brand forward has (correctly) identified that they need a brand-new digital presence, that the "esports" market umbrella is the place to position complicated and skill-intensive games like Magic, and that success in esports requires you follow certain aspects of the model like having events with large top-end purses. But because they're a big dumb publicly-traded company there's this fundamental wariness of just spending money on things to make them more successful, so they feel the need to hedge all their new expenditures by cutting back in other places -- thus the pattern of seemingly entirely random cuts that kirblar's been pointing out for a while, because they're having to justify their big new promotional expenses (large event purses and a ground-up digital platform) by shaving off expenses elsewhere.
A lot of these in the past have, I think, actually been pretty insignificant, but this one is assuredly a mistake. I wouldn't be surprised to see them walk it back pretty quickly. In fact, I wouldn't be surprised at all if the way this played out internally was that Hasbro asked them to give the pros a small haircut, and they turned it into a really big one with the hope that the resulting backlash would give them the cover to reverse the decision completely -- let's see what happens over the three months before PT EDM.