This is the way I see it,
All classes have access to miner and botanist abilities (not just cnj), and for one reason, productivity!
There are some hardcore gatherers out there, and the ability to use Truth of the Mountains/Forest to detect unspoiled nodes while farming other items as DoW/M will reduce any downtime while gathering.
I'd much rather be spanking sheep for fleece in Coerthas while waiting for that unspoiled rock to pop, than stand there with my pick out for hours..... Boring!!