I am installing a jet stage 2 chip on my '04 Dodge Ram w/4.7L. Jet recommends changing to a 180 degree thermostat but do you really have to change it? I understand that during winter the engine will run cooler but does replacing it have anything to do with the way the jet chip changes the air/fuel ration when it comes to engine temp?

I doubt it will make that much difference. Since it's easy to change thermostats, wait and see if it's needed.