Sorry for the ignorance, Windows user here. Can't you somehow downgrade?
For example, if you buy Windows 8.1 you have downgrade rights to every earlier version. All you do is speak with a person, say "I would like to activate windows" and they say ok. Its not a hassle unless you do it daily.
Also pricing is an issue: all recent desktop versions of MacOSX are either free or very inexpensive ($30 or less).
You could likewise say that filing an insurance claim is easy... sure, but for some folks even knowing to make the call is an undue burden - exactly how the vendor wants it.