Many people still rise up against what they think to be a kind of 'Trackback Hacking'.
Say for example (A) has published a post that supports Trackbacks by way of comment. Any time later, a blogger (B) might write a related post, not necessary wholly ‘dedicated’ to (A) post but with enough relevance so that (B) post can go as a Trackback in (A) comments, full stop.
Many people don’t like to receive Trackback on their blog if the (B) post doesn’t include full link and reference to their (A) post (e.g,.) while they accept ‘manual’ comments which in general link to the author's blog, precisely this kind of links which are ABSOLUTELY NOT RECIPROCAL.
I really don’t care about this obsolete Trackback rule and what I can see as a possible improvement (not only in bloggers’ mind) is a mechanism that will tie up Trackback and Tags in the wake of the Blogsphere development.
Indeed, with the development of 'standardized' Tags, one suitable application can consist in allowing Trackbacks on the basis of a (defined) level of Tags matching.
As an example, my configuration (for this post) would automatically accept any Trackback matching 75% of Tag list below.