Antti,
The issue with the cooking in camp is a entirly different mindset. The initial reason I was exposed to this technique is aggressive bear avoidance. For some areas (Yosimite Valley for isntance), this was paramount to a safe trip. Some in the UL community have adopted the same technique (not all of us mind you) but for a different reason(s).
The primary reason I use this technique is that you can choose your campsite with completely different criteria than your cooksite, so you can enjoy your meal on an exposed ridge line with a view while camping in a more protected area.
Mileage is the second reason, you can often eat on the trail at a excellent cooksite when your hungry, not necessarily when you are ready to bed down. That way after you've finished dinner you can still tick off a few miles before dark if you've still got some energy and aren't desiring a prolonged campsite atmosphere. This is a big deal during the winter months as the nights can be much longer in some areas and you simply may not need that much time in camp and instead can be skipping down the trail in the dusky light.



