Interesting that you say that. I experienced neither of those in the vehicles I've owned previously which include Ford, Chevy, 2xToyota, Acura, and now Chrysler. Increase in fan speed when on front defrost is the only thing I can say I've noticed in my previous vehicles. However, that's a non-issue.
I think your assumption that the temperature of the air produced by the system should change with each adjustment of the set temperature is incorrect.
I don't expect it to change, or at least for me to notice, with each increment. I did the 1F increments to test, so I can record at which point the temperature will start blowing cold or hot air. In my original post, I've noted that there was an abrupt switch from hot to cold when going from 66F-67F. In any case, when going from 80F to 70F I expect a noticeable difference in air temperature coming out of the vents. That's not the case with my Pacifica.
If the set temperature is above the current cabin temperature and hence the cabin requires heating, I would expect warm air to be produced. If the cabin temp is, for example, 60 degrees, I would not expect setting the temp to 80 to produce warmer air than setting the temp to 70 degrees - both call for significant heating of the cabin. Only when you lower the setpoint of the control below the current cabin temp (or just set it to "Lo") would I expect it to switch over to producing cooler air.
I currently own Acura MDX and Toyota Prius. If I set the temp to 80F in any of the two cars and drop it down to 70F, there will be a noticeable difference in the temperature of the air coming out of the vents regardless of the fact that cabin temp may be 60F. I think this is by design, no? I'm yet to own a car that blows only one level hot and one level cold depending on the cabin temperature. Having hottest air blow at you until the cabin reaches set temperature would be an awfully uncomfortable experience and bad design in my opinion. I'm not a mechanical engineer specializing in cars, but my guess is that there is some (or it should be) mixing of cold/hot air. If I get in my car on a cold winter day, I'd set climate to max temp and keep it that way until I feel warm. During that time it will blow the hottest air. Then, I'd drop it down to around 70, and as soon as I do that, the air temperature from the vents drops. It does not continue to blow the air of the same temperature as it was just because of the cabin temperature is still below the set temperature.