1) You couldn't be more wrong. Moment by moment psychology is and had been a part of the market from the beginning. The market is about INFORMATION, namely who knows something and who doesn't. Adding computers to the mix might have sped things up but hasn't fundamentally changed the game that's played.

2) I dont see any fundamental difference between multiple exchanges each with a dominant market marker and multiple market makers within a single exchange. In practical matters, retail investors dont select their exchange, their broker does.