Another drawback seems to be lack of controllers that make some games hard to play. This is yet another issue to be addressed by Apple-- They did add in DualShock and XBox controller support but that doesn't mean a lot unless users have access to those consoles in the first place, further solidifying Apple Arcade's place as a on-the-go gaming solution.
Because they've been repeatedly abused by free-to-play nonsense. Take out the IAPs and forced ads entirely and watch game quantity drop[0] while quality skyrockets. Customers might still be willing to buy back in, if all trust hasn't been eroded already.
[0]: Normally that's not a thing you want from a game/entertainment storefront, but I think the App Store (and Steam) is actually at the point where it would benefit from fewer games. Consumer confidence is at an all-time low.
In the early days of the app store getting high download counts was one of the only ways to get visibility. Which pushed the race to the bottom on pricing.
Once the big F2P players established themselves, they sucked all the air out of the ecosystem.
Arcade is, among other things, Apple's attempt to fix this. We will see how it turns out.
-W