Well, I think the most important thing in this regard is probably whether a particular document came to the attention of those in the east. People sometimes make too much of the language barrier, but then there's also the chance of making too little of it. For example, during the "middle ages," Augustine seems to have been the most quoted person in the west, and Gregory the theologian was the most quoted person in the east, yet westerners certainly never gave the same place to St. Gregory that the east did, and easterners were largely ignorant of Augustine's works. As we know, it wasn't like today, where one can do a translation, save it to disk, and then print off as many copies as needed. It was a wonderful thing to have a book written by one of your own countrymen, let alone one written by someone from a far off land who wrote in a foreign language. Let's not forget that the language barrier was originally intended (by God) to be just that: a barrier.
Even if the Easterners did know about a document, though, they'd obviously have to 1) agree with it, and 2) think highly of it. Just think of your own situation... of the many books you've read, how many do you quote regularly? Something would have to make a deep impression on a group--or at least have something that sets it apart, such as perhaps a clear articulation of the truth--for all the members of that group to be quoting it. The first one, agreeing with it, is obvious I guess, but stating the obvious isn't necessarily bad. 
The push for a celibate priesthood started rather early in the west... already in the fourth century we have councils (in Cordova, I think it was) instituting this practice. Whether the whole story concerning St. Paphnutius ever happened at the First Ecumenical Council or not, we can certainly say that the east had a very different view than the west on this issue from very early on. Thought of generally, though, if you had a western document that few people knew about, and it was slightly different in tone, and then on the other hand you had an eastern document that pretty much everyone knew about and accepted as valid and authentic (let's not forget that authenticity was not as assured at that point), which would you quote?
The exceptions seems to be those few documents that did squeak through, such as the Tome of Leo, and gained universal support. Of course, we Orthodox also venerate many other western saints, but the usage of their documents is still, on the whole, to a lesser extent than usage of eastern documents. This makes perfect sense to me in that people who we look to as authorities held fast to the tradition handed to them by their fathers. If their fathers, then, quoted Gregory the Theologian, and they grow up hearing Gregory the Theologian in their ears all the time, then it's pretty safe to say that they will know Gregory the Theologian and feel confident in quoting him. This might also explain the lack of quoting western authors today, as we are simply continuing the pattern set by our fathers. When you have a question of biblical interpretation, you consult Sts. John Chrysostom and Theophylact, not Bl. Jerome or Augustine. It's not necessarily a matter of right and wrong, that's just how it is. God raises up in each circumstance saints that the Church needs... these saints are thereafter given a place of prominence. This is not to deny other saints, but there must, of necessity, by some type of higher and lower levels as far as authority goes.
I don't quote the earlier papal documents because... well... I haven't ready any of them Of course I've read the "major ones," such as Clement's letter to the Corinthians, but by in large I've not read much by early western popes, except in histories, studies and anthologies. I imagine I am not alone in that. I agree with you in that these documents, read or unread, are of no less importance just because they happen to be from the west.
