I believe Heartrate Monitor has it right. PD has a very limited interaction system with other members. If profile pages had places to comment rather than PM's than I'm pretty sure traffic and comments would pick up. You can PM a person but it seems more Private and personal (hence Private Message XD ) and that's what I think puts people off to sending PM's to each other.
Also I think members should be notified when someone subscribes to their work, it would expose that artist to other members and would encourage them to interact with them :yes: But not so much favorites I think because... well it's just annoying to see five fave messages (Not that I don't appreciate it I do very very much! I just prefer comments more) and one comment message and then 15 comments on your page that just say "thanks for the fave!"
On a side note that doesn't have to do with the topic- I think writing comments will be a tough thing to fix cause it's not just PD that has trouble with people commenting on writing it's every art site out there even the strictly writing communities. People just don't have the time to read stories/poems (*in truth* don't feel like it ) and comment on them unless they already know the author to be an awesome one. But I think the ranking system will help it out alot but I wouldn't expect more than 5 comments.
