I didn’t surf much but it happened to me that I ended up in a place where I slept on a bare couch and had to use my jacket instead of blanket. While it would have been nice if the host provided the information it was also my fault because I didn’t ask. “Hey I didn’t find any info on your profile, do you have some pillow or a blanket?”. It was a good lesson for me and learnt from it. As Aleja mentioned, it’s surfer’s responsibility to make sure the place is suitable for them. If the host doesn’t provide that information- guest should ask and do not automatically assume that they will get beddings, towels or a shampoo.
Also, I have hosted over 100 guests and 95% of them were traveling without sleeping bags and majority of them without towels (which wasn’t problem for me, I was offering them) but I can imagine it would have caused a lot of misunderstanding (and possibly some negative references for me as well) if I didn’t have any beddings/towels and didn’t provide such an important information neither on my profile nor in our conversation.
We should definitely encourage active hosts to provide this kind of information either in “About my home”, “Sleeping arrangements” or “Additional information”. I like the idea you proposed: it would be nice to have some “hints” when filling out the home section: “Where will your guests sleep?”, “Describe your couch”, “Do your guests need to bring their sleeping bags/towels?” There might be people who never hosted before. This can be useful for new Couchers.