I consider it to be counter to what LJ is like, to not respond to people. I have a harder time in responding to reviews in TTH or the other places, but here it's more of an interaction thing. Also, it tends to draw people in to the story, which means more people read it, then I'm happier :P

Seriously, however, this interaction is a good way for me to gauge what I'm doing right, and also what's not coming across as well. It has helped me to grow as a writer.

Lastly, I get to use my snazy new icons on LJ :)

Another thing about my commenting on LJ -- as I respond to comments here, it helps to solidify the story in my mind.