I'm another one supporting the ensuite, purely from the "flexibility in travel" angle. We free camp when and where we can. Ensuites are a bonus for that reason. Sometimes you might be doing a very long walk with a shovel looking for some privacy if you don't have your own facilities. Honestly, I'm kind of over that...
Resale is also a good consideration. We're buying second-hand because from the research we've done new vans seem to depreciate a little quicker than we'd like. Slows down after a while, though. We're also handy enough to do some cosmetic refurbishments if necessary, so that goes in our favour. From watching the market it appears vans with weird layouts and lacking ensuites do not sell well - some "good" vans (at least manufacturer-wise) with odd layouts have been sitting for months. If you intend to sell your van down the track, it IS worth considering.
Also re: the smell, in theory a well functioning caravan ensuite shouldn't really smell much at all, if anything.
I know my comments won't change the minds of those who detest the idea of an ensuite or find them totally unnecessary, but they are the reasons why we wouldn't buy a van without one.