Be careful what you wish for.
Sideloading is likely to have results that leave users worse off. Side loading on Android has enabled pirating to the point where app developers go to a fermium model to try to make money. A premium Android app, according to some statistics can have upwards of a 90% pirating rate. I think that number is high, but even if it is in the 20 - 30% range that’s still a big hit to small developers. As a result, they move to subscription models, with a limited free app, to combat piracy.
Apple currently can revoke certificates if an app becomes problematic, as they did to Facebook when one of its apps was collecting data on children. Sideloading ends that, unless Apple builds in strict sandboxing and requires an Apple issued certificate to install and be allowed access to user data. Even then, once a certificate is issued a bad actor could change the app, as has happened in apps even on the App Store. At least then Apple can take action once they find out.
Then there is malware that mimics a popular app.
The current system is not perfect. There are flaws and problems have occurred. I’m not convinced what people are clamoring for is going to make things better for users or small developers. Big developers such as Epic can afford their own distribution system; although I suspect if some decide to go to an all in app purchase system that captures all the app revenue while letting the app be free to download, Apple will either not host their app or find other ways to generate revenue from the big developers. Which will no doubt result in more whining from the big developers.
Of course, if Epic can bypass Apple’s markup I have no doubt they will lower their prices accordingly, since they are looking out for the consumer in their fight against big bad Apple.