In our motorhome, the combination Microwave/Convection oven/fan vents outside and for the most part, I think that's a better system. I'm sure it's cheaper to vent it inside, and that's probably the manufacturer's reason for doing so. Your rig is quite a bit newer than ours, so I'm sure that in that time manufacturer's have found ways to build 'em cheaper in such a way that people won't find out about it until after they've bought 'em. That's just one of the ways they getcha! LOL
I can tell you this, if you ever decide to take it down to take a closer look, I highly recommend you have another STRONG set of arms available to assist you. The units are pretty heavy, but coupled with that is that they're bulky and it's hard to get a good hold on things while you're trying to loosen & remove screws.
Good Luck,
~Rick