I think both Apple and Google should make reviews optional.
Sure, give preference to the reviewed apps in the store, put a nice badge on it when it's reviewed, add a setting to allow unreviewed apps to install, prevent kids from installing unreviewed apps, etc, but at least let me upload my app when and how I want to.
The entire point of the app store is to further concentrate power with Apple.
Whether that is good or bad short term or long term can be debated separately, but it is fundamentally a shift of power away from independent developers towards a giant megacorporation. (I personally think app stores are fine but that the public has an interest in preventing any entity from having too much power, so it should be illegal to prevent sideloading.)
The point of the app store is to have a centralized AND TRUSTED distribution point for apps of the OS.
People can install non reviewed apps by using non-official app stores. There is good reason most people don't as these are plagued or perceived to be plagued with malware.
I want the safety and uniformity of knowing that have gone through the review process. If it not mandatory, no one will do it and I will lose the protection I have now.
It does include a different sort of review system though. Every app is built from source by the F-Droid maintainers and has a corresponding source code bundle availabile. This means that if you notice or suspect any shady behavior, you can review the code to find out the exact nature of the shadiness and alert people. Developers can't as easily claim that it was an unintentional bug that happened to accidentally siphon all private data from your device.
Sure, give preference to the reviewed apps in the store, put a nice badge on it when it's reviewed, add a setting to allow unreviewed apps to install, prevent kids from installing unreviewed apps, etc, but at least let me upload my app when and how I want to.