I think that crafting xp should be adjusted by materials you use, not just based on primary resources. People who use more expensive higher tier components should get more xp.
That is true especially for jewellery that still gives small xp for T4 and T5 gems and does not take into account whether you use silver, gold, platinum, ori components or their mix.
There is almost 0 reason to use gold or platinum because of that (and because T5 uses ori based on iron and starmetal instead of precious metals).
Anyway, I think this change would balance use of various crafting materials and increased usefulness of higher tier materials.