the hotel is purely a place of rest
You've hit it in a nutshell. Many of the hotels we now frequent struggle to meet that basic requirement. Whether it's a regional flight where you get the bare legal minimum 10 hrs rest, or a long haul to the other side of the world where your body is totally out of phase with the local time, sleep is a premium!
Here's a few counter-questions:
1. How can I get a decent rest when the curtains are so rubbish that I can't darken the room?
2. How can I get a decent rest when the temperature control is non-existent?
3. How can I get a decent rest when said temperature control unit is rattling all day & night?
4. How can I get a decent rest when the noise from the surrounding neighbourhood can't be filtered from my room?
5. How can I feel safe going out for food at some weird hour (jet-lag) because if I turn right instead of left out the front door I'm in gang territory?
I suggest you lookup "Motel 6" in wikipedia. Then you'll have an idea of some of the places we stay.