Klaus, are you suggesting that users should always upgrade right away?
What I am suggesting is that users should always try to run the highest version of OS X that their particular Mac can run, not just for the 'extra features' but also for security reasons, i.e. available security updates, which Apple do not supply for outdated versions like Tiger or Leopard.
Are they also supposed to call Apple directly?
If they already have Snow Leopard they have no reason to call Apple!
And what about those users who have Snow Leopard and want to upgrade, but don't have sufficient hardware to run Mountain Lion? Did they wait too long?
That is a question of money. Not all of us can afford, or can see the necessity, of buying the latest MacBook, iMac or whatever. What our Mac did yesterday it will also do tomorrow! The 'built-in obsolescence' of a Mac used to be about 5 years, but is now only about two years or sometimes less. To replace a computer that often is, IMO, overkill, technically speaking, but it may appeal to rich fashion victims! 🙂