I'll tell ya what. Having written for a dozen different Mac 'zines, and worked for Apple I'll send you a free copy of every paid update from system 6 through system 9.
Expect 4 or 5.
Apple has BOUGHT companies which were already survivng providing software exclusivly for workstations that's WHY apple is profitable now. These mission critical apps are Mac Only.
1) Version number conventions from pre-Mac OS X do not apply to Mac OS X. You're kidding yourself. One could easily reversion the Mac OS X series of operating systems as, Mac OS X v.1, v.2, v.3, etc. Those would correspond to 10.1, 10.2, 10.3... Your argument is faulty. Every one of the charged updates are major updates, and are not incremental updates, as you claim. The incremental updates are still free, and are noted in the new version number convention as 10.x.y, with "y" being the incremental version number.
2) As I already said, and find myself repeating - Apple cannot both produce an operating system and the software to run on it, and remain profitable without the hardware portion of their business. Their business model relies on it, and your proposal would remove the hardware aspect of their model - and would eventually bankrupt their business. In order to do as you propose, Apple would have to scrap the Mac OS and produce software only for Windows, because they'd have no means of maintaining the development of an OS, if their only business was based on software sales.
Those "mission critical" apps may be Mac only, but as I pointed out - they represent a very tiny portion of the Mac market, and your strategy would shrink Apple's marke share from where it is, to something a lot smaller.
You have no idea what you're talking about. In order for Apple to continue to do well, they have to continue to leverage their OS and Hardware business together, with the professional suite of applications there to add to the total value of their product line. Apple is a hardware company which makes some software.