I've done this, without feedback. The reason was that doctors seem to come in several varieties when it comes to bringing their ego to work and my doctor had a serious case of that. I was dehydrated after an operation and when he asked if he could do something for me I asked for some water, the doctor then ordered someone else not in the room to come and get me a glass of water. He couldn't be bothered to walk to the sink and do it for me because that sort of thing was beneath him, he was a doctor after all, not some lowly nurse.

That would have been hard to argue as sufficient reason to switch but I figured that if his primary worry in a situation where a patient has clearly expressed a need is his perception then he shouldn't have become a doctor in the first place and likely that would get in the way of him providing care.

I've talked this over with a nurse friend of mine and they totally confirmed that this is normal, doctors, especially in a hospital setting, are on top of a hierarchy that tends to self-reinforce their importance. And yes, they are important. But in the end what is most important is that they realize that the only reason they have a job is because someone else is in trouble and that some humility goes a very long way towards establishing real rapport.

The one thing that stood out for me on this subject that I read about a while ago (not sure if it was in a book or online) was that actually being in the hospital as a patient immediately made doctors a much better doctor for their patients.

Dogfooding works, even for doctors.

Another reason why people don't leave feedback: they don't want to get into an argument, they just want to switch and they already have enough on their plates and fortunately in many places they have that right.