Personally I don't care whatever happens as I purchase Apple devices knowing I can't sideload, but I do believe the option should be there. Not for the alternative app stores, but because Apple can reject apps from their App Store for any other reason than security and can get political or in defense of their own interests.
The 'then don't buy an iPhone' argument is not valid when you can indeed purchase an iPhone knowing it supports a particular app, then have it taken away from you because Apple decided so. Allowing the option to sideload is better for everyone. Nobody is going to go through the hoops of sideloading stuff when the App Store is right there, unless they need to.
P.S. It is scam apps galore on the App Store. Sure, it's not as bad as Play Store, but it's not that much better either and on the iOS side those apps mysteriously tend to rank high and be among the first ones that you find when searching for an app with a particular function. Apple could have interest in ranking a PDF scanner app that costs 60 euros/month (insanity) as the first result when you search for an app that does exactly the same thing the inbuilt Notes app or Ad*be's equivalent.
The 'then don't buy an iPhone' argument is not valid when you can indeed purchase an iPhone knowing it supports a particular app, then have it taken away from you because Apple decided so. Allowing the option to sideload is better for everyone. Nobody is going to go through the hoops of sideloading stuff when the App Store is right there, unless they need to.
P.S. It is scam apps galore on the App Store. Sure, it's not as bad as Play Store, but it's not that much better either and on the iOS side those apps mysteriously tend to rank high and be among the first ones that you find when searching for an app with a particular function. Apple could have interest in ranking a PDF scanner app that costs 60 euros/month (insanity) as the first result when you search for an app that does exactly the same thing the inbuilt Notes app or Ad*be's equivalent.