I don't see any problem with this. I refuse to farm ARF on the basis that it's boring, and I suspect that if scripture converted to lore on the other dungeons, people fed up of farming arf would be able to farm other dungeons instead, which could lead to better queues for other lv60 dungeons. The amount you would get from current ex dungeons would be 130 (80+50), which is still short of arf's 160 (150+10). While it might not get more people in to content (as people drop out of content sooner for having more lore), the change might push people out of farming arf into other dungeons, which could well make up for it. As for other lv60 dungeons, the scripture given is so pathetically low getting them as lore wouldn't even be noticeable.

In short, I think this would give people more options for lore farming, and that would encourage lore farming, not discourage it, as people wouldn't burn out on doing just the one thing over and over.