Ok, here's the technical low-down from someone who used to work with Caligula & Hoss and also HT (and who is also currently programming his own game) :
First - OpenGL vs D3D. OpenGL IS easier to develop with than D3D. Many's the time that I've coded something with D3D, shook my head, and said "what the f*ck were they thinking". The problem with OpenGL is that there isn't a _complete_ set of functionality of graphic operations supported by the vid cards for OpenGL. Something cool that's available in D3D just isn't supported on the card for OpenGL. That takes away from the eye candy. Also, 2D operations in OpenGL are a pain in the ass. This comment comes from Random (former ICI, now MotorSims). MS has said that they're going to produce a product that will allow OpenGL's full functionality (Fire-something) but I suspect it will be a layer of OpenGL on top of D3D, which would slow the game down.
Second - PCs vs Macs: To start, I like the Mac, but graphics of OpenGL vs D3D aren't the only issues in implementing a game. There are also different methods to do dialogs, communication, game installation, input device polling and configuration, system key conflicts, and system querying (ie does this system even have a joystick). Even going OpenGL "from the start" wouldn't solve these divergences.
Third - programmers: Programmers are in high demand in the industry and Mac programmers even more so. Hense, more expensive. An average salary for an experienced programmer these days runs from 55K to 80K (non-consultant). True, you can find Mac programmers like Hoss that will work for less than he could get because he loves the game field, but that makes programming for the Mac even less feasible if you try finding another coder like him.
These aren't all the issues involved but it touches on some of the main points. I've yakked with HT on his approaches to platform independence and can at least assure you the man has got it together on this issue. Big time. He has _no_ hatred for the Mac platform and has as many complaints about D3D that I do.
Take Pyro's post for exactly what it is - a _current_ position statement not a policy carved on some stone tablet.
Hope this helps . . .
-sudz-