But some Aes Sedai say that they have aptitude for Healing though they've never been interested in it, so it's probably not the case. And the Asha'man who were skilled with creating weapons with the Power were not blacksmiths.

One could debate that Ishamael was a philosopher and studied the meaning of life and thus had an affinity for TAR and other dimensions.

I guess you're not alluding to a single example, but overall I think your theory could be disproven.

Its also interesting to note that Healing offers up a higher chance with other Talents. We know that more than half of the women forced to make cuendillar were Yellow ajah and that Semirhage was one of the few people who could block a gateway. I wonder if empathy allows a greater alignment with the Pattern and thus makes the channeler overall more powerful? Now that Rand has become the avatar of the Pattern, he's become incredibly powerful, and this may be the reason.