My second point was that the Nag Hammadi texts are in Coptic, a language not as accessible to NT scholars as the language of the DSS.
Okay. But so what. Learn Coptic.
I have been a strong advocate that Coptic become a regular language in any Christian Origins curriculum. It should not be considered an additional language to Greek and Hebrew. Over fifty early Christian texts are written in Coptic, and this doesn't even begin to include the early monastic literature, although the early monastic literature is farther removed from the study of Christian Origins than the second and third century literature from NH and the Tchacos Codex.
If a scholar doesn't learn Coptic, he or she can only include the Greek literature in any discussion of early Christianity and Christian Origins. This means that his or her study of the period is lopsided, including only the NT texts and the early fathers. Not knowing how to read Coptic is not an excuse for excluding almost half the literature from full consideration in our reconstruction of early Christianity.
If you want to learn Coptic, it is taught at many major universities. The International Association of Coptic Studies keeps a web page of all places where Coptic is taught. There is one very good learning grammar by Thomas Lambdin. There is another that has just been published by Bentley Layton, although I have not received my desk copy yet to comment on its usefulness as a learning grammar. Crum has been reprinted. There are also online resources available. I have all of these links here. Click and scroll down to Coptic History, Literature, and Art - General Resources/Coptic Language Resources.
Update: July 30, 2007
Mark Goodacre here also recommends that all graduate students in Christian Origins learn Coptic early in their career.