I actually find it be laziness. There different calibers of PR firms that I spoke with that say they ignore TC altogether because of the horrible type of traffic they have -- as in, mostly international, mostly incompatible with their client's need, mostly RSS readers, and mostly non-convertible. They rather go on the hunt of finding the right writers in the right fields/markets to get them to prep for a story.

If your PR firm's first, second, or even third, suggestion for you is to pitch to the biggest tech blog: fire them.