Two things I wanted to note: I have had laundry not appear despite the presence of a washer, dryer and hamper. I assumed this was just a really nice glitch since I wanted the realism of the equipment, but it was nice not to have to actually do laundry. That said, at some point (probably after a patch), it did start appearing.
The second thing I wanted to add is in addition to the moodlets folcon mentioned. Your sims not only get clean clothes moodlets but an additional clean sheets moodlet while sleeping. The moodlet will start every time they change clothes, so just changing from pajamas to everyday and back again guarantees there's pretty much always a positive moodlet. And, in my experience, there's no need to do laundry every day. Once or twice a week is usually okay for my families and I've never had that moodlet run out. If you're looking to boost lifetime reward points through atmosphere rather than relying on wishes, laundry is a definite plus.