Currently, when someone provides a comment on a page, you have no idea if the user will be notified if you reply to his or her comment. So, that forces me to reply through email as well, which totally defeats the purpose of using the comments feature. This is probably a longer offline discussion, but the easy solution right now would be to make the "Watch this page" checked by default when you post a comment. This assumes that if a user cares enough about leaving a comment on a page, the user will most likely want to watch it. The current check box could also be changed to "Watch this page (receive replies to your comment)" or something like that.