They're putting short term profits ahead of the long game. Long before the iPhone came out OS X came bundled with XCode. Anyone wanting to learn to code for the Mac could do it out of the box starting with 10.3. For a college student that wasn't quite ready to get started in Linux (And this was Linux 2003 mind you) it was amazing that I could compile stuff out of the box without dealing with cygwin on Windows XP.
If you coded in XCode the PPC-64, x86 and x86-64 migrations were relatively painless. When the iPhone finally got a dev kit the tools had been out for 5+ years. People were able to hop in to iPhone development. Distributed builds over ZeroConf have been supported for a while as well. Have a dozen machines sitting idle? Hit compile and distribute the load.
Apple has fallen completely on their face supporting the people that make the pretty widget iPhone apps. Unless they start churning out development tools there isn't going to be a machine to do iOS n+2 development on.