Everyone uses their TC differently, but many of us never need a generator for more than a few minutes at a time. That’s where the builtin shines. I already have a propane stove, fridge, furnace, and hot water heater, so it makes sense to use a propane generator for those few minutes to run a microwave, top off the battery etc.
With few exceptions, I can’t think of any time that I would be running a generator for hours. Most campgrounds don’t allow it, and besides, I’m out doing things when it is hot. If I’m forced to go out when it is really hot, I’m going to pay the few bucks extra for hookups. For the cases when I’m not at a typical campground, I just find a cooler spot. Again, no sense in camping in the sun when you don’t have to.
Finally, if I’m not moving around and don’t need mobility, I’d probably go with a much larger unit like a Class A, fifth wheel, etc.