I do think it also comes down to the quality threshold. A lot of indie developers go for the portable market because the fidelity and standards are probably two generations behind what is expected of a PC or Console release. You can make a game that looks like something just ahead of the SNES or PS2 curve and it's fine for a portable game. It doesn't require a huge development team. Things like that.
I do agree, I would have gladly purchased Requiem for the PC or a PC port of Aliens : Extermination. (I've never seen one of the cabinets anywhere.)
