Add to the lumpy/heavy aspect the nasty texture of the cover. Those things might have been nice to touch or look at on day one, but after the first wash, they're just gross. Assuming they get washed after every stay!

HI and HGI also, should do what Hiltons and others do - wrap the duvet inbetween two sheets. That has to be easier to change when a room is turned than dealing with a cover. Again, assuming they remove and wash it after each departing guest.