Just out of curiosity why do most people make their home docking stations with the factory AC power supply? Is it just the fact that they prefer it in "home" mode or is there something else I need to know?

Yes, that's a big part of it. The automatic home/car mode selection is an important feature for some folks.

The home/car thing has a domino effect: Serial port speed, serial port power-on-upgrade ability, etc.