The writing of an operating system is more than complicated and the prime OS is for Windows.
Mac/Apple is growing in usage but still below 10% of the computers in the world. That alone
causes programmers for companies to spend time working out the changes necessary in their
programs to work on Windows.
The new OX Leopard software has glitches, which are theoretically being solved with an upcoming
update of near 450 MB's . . so, many of us might wish to wait a bit for Tiger to settle down.