Yes, the APIs are separated and a full API node requires an extra server which is much, much faster than a normal witness server. They also (in most cases) provide an extra seed node just for spreading the blocks to other nodes. So we have three servers...

I think it would not change much, if I would add the information in the witness list, because it is already a well known problem. It may even be that some witnesses are really good in what they are doing but technically not on a level to maintain a full node. Difficult to say and define what is a 'right' or 'wrong' way for them.

That's why I came to the idea that we might need a reward for full node maintainers, so that there is a good reason for people that are able to provide a stable endpoint to do so. Even non-witnesses should have the option in my eyes.