There was a 3-4 page response about the built-in generator option just a couple weeks ago. It's about $4,000.00 on the typical build sheets. The factors of weight, reliability, noise and shared fuel with the camper itself were all considered. As with any option, it's the value you see in it.
For what it's worth, I see more oven deletes than micro in new camper layouts. The cooktop and dual-purpose microwave seem to be the favored choice in new campers.
This is the fun part until you get the camper. Then you get to experience a better fun! Good luck-Mike