It really does undermine the legitimacy of their claims that they should be the only source of apps, for safety reasons, of course. That reason alone is why they "should be better"; It would serve to legitimize their dogma.

Apple built up a really strong brand by not doing this kind of thing for a while. They get to charge twice as much money for half as much performance because they made sure their products felt nice and intuitive to use. Now they’re willing to destroy the most valuable brand in the world to make crypto money? It makes absolutely no sense, even accounting for greed.

Also, I’m sure this kind of thing hurts their prospects in antitrust cases (like in the EU)