Just creating a tenant is a PITA and you get a default tenant you can't change without paying for Microsoft 365? Then you have subscriptions, Microsoft partners, Enteprise vs individual accounts, etc. All mixed with legacy AD naming and renaming, documentation with outdated screenshots, Microsoft Partners bullshit.
What exactly ist a PITA when creating a tenant? It's straightforward.
And what do you mean by default tenant that you cannot change unless you pay? Nothing comes to mind where that would be the case.
Are you sure you're not just using it wrong?
I agree needing an account to create a tenant is not ideal. But that's nothing more than a minor inconvenience. If these are the big problems you make out with M365, then I think I can just shrug your opinion away.
And yes they have different types of accounts and methods of billing. Their customer base is probably in the hundreds of millions. People are going to want options. I don't really see the issue there.