If you need to connect to a domain infrastructure, you won't be buying a home edition of Windows - or any version of Mac OS X - in the first place, so the whole basis of your statement is null and void. You will directly buy a professional or enterprise edition, and companies usually buy those through a volume license contract at 'slightly' different prices than you will find on Amazon.
While I agree that the upgrade from Vista to 7 should also only have cost 29 bucks or should have been given out for free for Vista users, the upgrade from XP to Vista/7 was much more significant than the upgrades from Leopard to Snow Leopard to Lion were and the full upgrade price for Vista was justified - especially after all those years of development.
The move from Tiger to Leopard brought significant architectural changes, just like the move from XP to Vista did. But SL and Lion bring mostly cosmetic changes (in the case of Lion even some that make the whole system look uglier instead of better) and a few visual gimmicks, but nothing really significant. Basically, both Snow Leopard and Lion are just service packs for Leopard, like Windows 7 is just a usability and performance service pack for Vista.
But how do your 29 bucks upgrades look when you compare them with the free Ubuntu upgrades? Ubuntu evolves faster and with even more eye candy than OS X and Windows together, and it also is a much more secure, robust and faster platform than both Windows and OS X. Since most people spend most of their time in the web browser anyway, the arguments for the expensive platforms OS X and Windows are rapidly running against zero.
Anyway, while Lion is not an overly exciting upgrade, it's certainly not a bad update and it also is among the better of Apple's dot zero releases. But it is all that even without the annoying childish mocking of Microsoft Windows.
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