I am of the opinion that the only fair option is to allow 3rd party stores with the same permissions as the official app store.
Apples curation isn't (as they suggest) preventing malware, theft of information, etc - this if verifiably false given recent history with apps like tiktok stealing clipboard content. The ability to change content of payment screens post-approval (as epic have just done) also means that curation isnt stopping apps from potentially injecting phishing, etc, either. In short, they are just choosing what they like - just as any 3rd party store could do.
The security comes from the sandbox (and surrounding permissions) - not from the curation.
Jobs originally said that the aim of the 30% was to cover costs of running the store. It is evident from the MASSIVE profits that this is no longer the case.
The size of these app marketplaces (I dont just mean apple) make them markets in their own right - its about time they were recognised and treated as such.