IMS, my college geometry and algebra would disply XY coordinates on a plane facing the observer. This makes 2D game programming a bit more intuitive despite the reversed Y component. But when the courses began to deal with a third dimension the XY mapping was laid out on the horizontal plane and Z would be up/down. I wasn't something I had difficulty in switching to.
AAR, I suppose what it comes down to is what you were introduced to first as seeming to be the system of preference. When I was in college computer monitor coordinates weren't of great interest considering that the kind of games we can produce nowadays weren't even possible. So I went for a long time using what was basically a mathematical coordinate system and being comfortable with it. Now that I have to think in monitor terms I have to constantly remind myself which direction the positive Z axis is in.
Lilith, Night Butterfly
I'm not a programmer but I play one in the office