What do you think of duvets?

For those who may not know, a duvet is a combination bed spread and top sheet, sewn together with one end left open. It makes a cover that slips over a plush cushion. The end result like a really cozy comforter that you can take the cover off of.
When a guest leaves they take the cover off off to wash, and put a new one on each day.
Hotels have started using them to control bedbugs and such. Someone also commented that it does a better job of protecting us from other guests ex-body fluids.

However, I don’t buy into this. For one thing, when the hotels just used a regular bed spread, blanket and sheets, ALL of those can be washed. With a duvet, however, only the cover can be washed. The plush cushion that the duvet covers can’t be washed, or you end up with unattractive lumps. This is the bed that greeted us when we walked into our hotel room at the Hampton over the weekend. It was comfortable, but very unattractive. In short, it looks very messy.
I would prefer to sleep in a bed where all the covers can be washed.

So do you think duvets are self defeating?