The reason German (and other continental vans) are 'not so well-equipped' is that our European caravanning counterparts tend not to use their van to 'live in' but just as a mobile bedroom, spending most of the day outside - even in the winter when they spend full days on the ski-slopes or walking. If you look on European campsites most continental vans don't even have a full awning, simply a sun canopy to sit under if it rains. Most Dutch, Germans and French spend little time actually inside the van, even preparing food, cooking and eating outside. So, they don't need an oven, microwave, four burner hob, luxuriously appointed upholstery and fancy curtains, etc., and all the other equipment we Brits consider essential. Manufacturers concentrate the cash on the insulation (against both excessive warmth in the summer and cold in the winter), better heating, internal water and waste systems, and general 'strength' of build.
I wouldn't know which caravans hold their value best - in a changing market it could be anybody's guess, but if you get the right layout of van, and keep it for as long as you can, then you really won't worry too much about depreciation anyway.
We have a fixed bed, and love it. We use normal sheets and duvet, and leave the bed tidily made up. We have to make it up twice at the most in a two week holiday. When we went in for cushion wrestling then this was a twice daily chore - making and unmaking it, and putting bedding away (unless you use sleeping bags, which are not what I'd like). We have a comfortable mattress, and a proper wooden partition which separates it from the rest of the van - and actually if you take Geist's hypothesis, it's actually ready (all day) for being 'active' and engaging in 'intimate social gatherings' or even for general sprawling!