3 points.
1. Though this announcement was from May 8, 2018, their current
Signup Page still lists it as "starting later this year". Not sure what to make of that, and I'm not signing up to find out. It seems to me that it should have happened last year and they shouldn't still be advertising it as "later this year". Maybe it's nothing more than a missed page that should have been updated months back.
2. Games are still going at the old 30% rate. So is everything Xbox related. My guess is that they're making more from games than other applications. No point in giving up profit on your money makers. It will subsidize their loses on the other side. Just my speculation; I have no actual facts to support that. Not that it really matters much.
3. They're not doing this as a way of thanking developers. Instead it seems to be to a tactic to be relevant once again.
Microsoft’s Windows Store has been struggling to attract developers for years now, and Microsoft is now radically overhauling how it takes a revenue cut from app developers. Microsoft is essentially having a sale (i.e. lowering their profits) to draw in customers (i.e. developers). As a developer myself, in today's world, I'd rather have 70% of Apple's pie than 95% of Microsoft's.
Microsoft lowering their take doesn't seem to be a good argument for Apple to do the same. The people on the top shouldn't necessarily mimic the business practices of those on the bottom. They don't need to make the same desperate moves. Not knowing Apple's costs, I don't know if 30% is fair of not. And really, "fair" will vary from person to person. But I know there are real costs associated with their services.
For the general conversation, there are two costs getting mixed up quite a bit. If you want your app(s) in the App Store, that's $99/year. Or for $299/year, you get those benefits plus the ability develop apps for your employees and distribute them to your employees
only (as Google and Facebook recently learned) outside the App Store. I've seen a lot of people saying the 30% is for server costs, networking costs, distribution costs, infrastructure, etc. That's what the $99 is for. To be on the store and all the benefits that gets you.
The 30% is what they take if you get money from the customer for buying your app, in-app purchases or subscriptions (which can be less than 30%). That is their payment processing fee and pays for things like a fraud department, a customer service department, credit card processing, collecting and distributing money all around the globe (or disc if you prefer) and so on. They don't take 30% to have it in the store. They take 30% if they're handling money on your behalf. If they don't need to be the middleman in your financial transaction (like in the case of Uber/Lyft for example) they don't take 30%. It's really that simple.