This has bothered me for a long time, too. In the meantime I get detailed feedback from the two persons closest to my heart and so I'm not very desperate for comments anymore.
Of course I do like it if someone like the aforementioned Jimmy Jump jumps in and gives his two cents (and usually it's much more than just two cents), but it's not what motivates me. I would write just as much if only those two person would ever read my scribblings.

Maybe the first idea could work. Dunno, really. It wouldn't motivate me to write a comment. Maybe it motivates others.

The second idea: No thanks. Been there, done that. For a while I complained about not getting feedback so much that my Master made me write five comments for every story I posted. It sucked big time, mostly because I had to read those five stories first and I don't really like to read erotica.

So, no, I don't comment. Sounds selfish, but after investing quite a large chunk of my spare time in writing a story I think I am entitled to just lean back, read a story once in a while and just enjoy it without having to write a comment.

Writing a proper comment takes time. Time which I rather spend on writing myself, to be honest. I do however reply to every comment I get. Or at least I try to.

And as Venom pointed out: I rather have one detailed feedback than 20 "nice story"-comments.

Not sure about the rating box. I've gotten a 1 rating once, just because one of my stories was called "Partygirl" but was written in German and the reader was so pissed off by this that he clicked the '1'. I can do without such crap, too.