I have a friend that modified a cargo trailer and it just seemed like a ridiculous exercise especially from an economics standpoint, and he didn't put in any plumbing. I definitely want plumbing.
My predilection for "stripped down" is rooted in my overall philosophy in life and especially my outdoor life... if I don't need it, why carry it? Among my favorite outdoor pursuits are backpacking, mountain biking and hiking. These are all activities where less is more and I don't carry something that I am never going to use. Definitely have to take the essentials every time we go out, but only the essentials and if there is a lighter, more compact version of something, I am always seeking out those things and replacing the older, heavier, bulkier item. So the same applies to my choice of RV. I really don't want a larger tow vehicle (but will cross that bridge when and if I come to it) and so if I can make my RV lighter by not having AC, MW, RVQ, Radio, etc. then that is what I will do. Just the essentials is my mantra. Beds, a toilet (for the wife) and a shower. To be totally honest, a stove, sink and table are all superfluous to me too, but I realize that I won't find something with a toilet and a shower that doesn't have those things too.
I guess my reservations about a pop-up are 2 main things. Do they come with showers? And will I constantly have wet sleeping gear because the kids can't stay away from the sides when it rains?