Yes, perfectly true. But would you rather have thousands of average apps, or one hundred really good ones?
There is some amazing software for windows, but let's face it there's a LOT of crap too, most large developers see the potential of the macintosh and develop applications for it, some even primarily (Adobe, Macromedia, even Microsoft) however due to the Windows market being larger (and therefore meaning more profit) the majority of companies will develop for that platform.
This does in no way mean that software for the mac does not exist for job-X, software is also not hard to find, with sites like versiontracker and macupdate all you need to do is search.
There are varying factors, the main on is money, people don't realise that Mac's last a LONG time and that the MHz mean nothing, I know someone who until a few weeks ago was running a 500MHz G4 (He gave into temptation and treated himself to a dual 2.0 G5 though
) and had no problems with it, and the great thing is, that he will be able to sell that 500MHz, second hand, for nearly as much as he paid for it. As a matter of fact, my PowerMac is currently re-sellable for more than I paid for it, and probably will be for a while. At the end of the day, you DO get what you pay for.
Most people aren't educated that PPC even exists, and therefore think that a 3.0GHz P4 is faster than a 2.5GHz G5 which isn't the case, so they think that the mac isn't worth the money being asked for.