I think the truck campers are meant for someone that already has (or otherwise needs) a truck - the truck is useful even when you're not camping.
Also, a lot of the price for the truck comes from options -- you can buy a base model V-8 F-250 for under $40K and add a $30K camper shell for the price of that motorhome. The camper is going to be more cramped than the motorhome, but you can use the truck when you're not camping so it's a trade-off.
E-350 cutaways aren't that expensive, they cost around $30K (and will be equipped about the same as that F-250 base model)
For me, the tradeoff was easy, I don't need (or want) a truck, so I got a motorhome.