I've heard that to learn Ancient Elf motif, you need to have 8 rank in all 3 main crafts. Is it correct? And I also want to ask about the terms of daedric and barbaric motifs.
Hmm I have not heard of this but in general it wouldn't be an issue I would think.
By the time most players get there hands on any of those motifs they are probably above level 30 and if you have been deconstructing weapons and armor then lvl8 in wood, clothing and BS should be no problem.
It would be interesting to find out for sure though...
I was VR1 with around 28-31 in blacksmith/clothier/woodworking when I found a primal motif, and did not notice any requirements attached to the tooltip stating as such, nor have I noticed them for any of the other 11-14 motif books that people link in zone chat to sell.