In my case these posts are often unread also because I overlooked them, or because I didn't have time to wade through everything the previous time - an effect of the huge amount of posts here at ITT. Unless you sit down and read it several times a day there'll be a big backlog.

For me, the feature you describe is a very good feature, and I can't see why you would want it to go away - it's not like it's in the way of anything else, tacked at the end of the last page(s) as it is.

In any case, if you don't want to see it you simply click 'Mark Forums Read' in 'Quick Links' when you're done with reading new posts. The next time you select new posts you won't see any of those unread, older posts.