I would match rather sign up for a subscription through the iOS ecosystem, where I can easily and realisably cancel that subscription through Apple themselves as opposed to entering my credit card info and figuring out how to cancel for each and every application differently.

FWIW, people usually like to support lots of payment options, particularly ones that already have the customer's payment details on file and that the customer likes using, so as long as you are OK with the realization that people who pay not through Apple are going to pay like 10-25% less (depending on any number of factors, as Apple is honestly offering non-0 value) than you (which I honestly doubt, but you need to remember that a key part of this isn't the functionality but the cost: a ton of the money you are paying is just going to Apple right now) I would be shocked if companies didn't throw in Apple's IAP as a (more expensive) option. Like: for my store (Cydia), I never required developers to use my payment options (as that would be a horrible and anit-competitive thing to do) but they did anyway because users liked them so much and they were easy for the developer and I actually solved problems they had (license transfer, some of the customer support, etc.).

Personally I would prefer to sign up to a subscription via PayPal, where I can easily manage the subscription though a web site instead opening the "Music" app (!?!) and navigating through that nightmare

I am confused, are you saying that the only way to manage your subscriptions in iOS is via the music app and not the App Store?

Have you looked at Google play store, in comparison? Apple is still doing 100x better job. 100% cleanliness is utopia but I will take an App Store that weeds out lot of contaminated apps than every other app being contaminated in some sort of way.

I do think that the apple app store has better quality apps. But to be frank, those 3 day trial autorenew apps are definitely more common on iOS.

There are so many highly rated iOS apps that look great and where you can't even get past the initial stage without having to sign up to a subscription without even know what it is.

Is someone taking the App Store from you? Does adding alternative options somehow corrupt the original App Store?

There could be an argument that allowing alternative stores would just mean every app would switch to those and be able to work around Apple's rules and act against consumers' best interests.

However, the fact that Apple only enforces the rules when it benefits them as opposed to consumers (so they are happy to turn a blind eye to spyware, but will crack down immediately on alternative payment options) means that in practice I don't see it making the situation any worse.

>There could be an argument that allowing alternative stores would just mean every app would switch to those

Which is a ridiculous argument as the network effects and default preference status of the App Store mean it'll still be pretty much a requirement to publish there if you want any users.

Not really.

Apple currently has the market power to keep Facebook and other similar scum at bay if they chose to (unfortunately, they're not doing anywhere near enough on this front).

Opening the floodgates to alternate stores would simply mean every mainstream service out there would require you to use that alternate store (isolated from Apple's enforcement) where all kinds of nastiness is permitted.

Nobody is proposing that the Apple app store should go away, or that other stores shouldn't be curated. (E.g. exactly because the play store is as it is, on Android I go look at F-Droid first, because if it has something I trust it more)