Apple should be commended for making their tools pleasant and easy to use. This encourages development. I was very pleased when I could download the toolset for free, instead of forking over $$$ for Visual Studio.
This discussion so far has largely focused on consumer software. I think one big factor holding back adoption of Unix (incl. OSX) is the lack of Visual Basic. There is a HUGE amount of code out there in VB, especially in businesses. Having Office for the Mac is great, but if it can't run your company's set of macros or add-ins, it'll be of limited use.