Yeah, I agree with you that feedback is a key part of a writer's day and does greatly improve their writing by hearing what others have to say about their work.
However, its VERY hard to know what others think if they don't review. I rarely post any of my stories here because people didn't review when I did. I post pretty much 100% of my stories on fanfiction.net since I get a lot more feedback there.
Writing stories gives me a great deal of joy and I would like to know from people who read my work what they liked about it and why, and not just give a cut and dry description with no details because those are very hard to figure out and are usually impossible to come to the conclusion of what the reviewer actually meant to say when they weren't clear in their review because they were so vague. Detail to me is key!