Most software developers want that - or, more specifically, all the benefits of Linux with mainstream hardware and application support. What's wrong with that?
Not only does it have poor support for common hardware, it has artificially restricted support. What it does support, it supports reasonably well, but that hardly qualifies OSX as a system that supports mainstream hardware.
If you want to write a cross-platform app, I argue that GTK is still not a very good solution. I wonder how Adobe is progressing with their cross-platform Cocoa-based CS5.
OS X does provide most of the benefits of Linux, except for large portions of the OS being closed source.
You get a terminal with bash or whatever shell you wish, which works great (none of the Cygwin crap). You can compile most non-GUI Linux apps for OS X (and many GUI ones). Etc.
I rarely run into things that I can do on Linux that I can't do on OS X.
