I thought all hotels changed sheets every day! You pay the same rate for the room each day so the room should be cleaned every day and fresh sheets and towels every day also!
If the sheets were changed on a daily basis, the daily room rate would be increased to offset the cost of cleaning all those sheets. Personally, as long as the sheets are changed after the previous occupants have vacated the room, I'm happy - better than paying higher room rates.
However, I do agree that we should have fresh towels everyday. Damp towels breed germs.