As someone who uses this feature a LOT. I do wish there were an easy way to access it from whatever page you're on like you can with the mobile theme. Yes, I know there's a way to do it, but it would be a lot easier if there were just a link at the top or bottom of the page like the mobile section. I don't really use bookmarks and I'm not aware of a way to access it from the desktop version that's nearly as fast an easy.
Oh and alasdairm, yes with a direct link you can access the feature on the desktop theme, but not by going to view your posts in your profile page. That only shows you your recent posts but not if there have been new replies and in order of new replies. Similar but not quite as useful.
As for the original poster, I don't wanna speak on behalf of the bluelight admins, I'm not anyone in authority here, but doing what you suggest might well require some basic web programming know how, and there might not be anyone in authority with those skills. I'm not saying that's the case, I don't know, and like you I would like to see this feature made more accessable, but you asked why it hasn't been done and so I'm saying that it might not be as simple as it sounds. There might not be someone in authority with the skills to do it and it might not be something you can just switch on.