I thought that Red prince would benefit from it because of his Fire breath skill, even though the description says it is based on Intelligence for damage.

Is it?

Maybe the stats are like they are so so you make a Pyro hybrid while not being forced to invest heavily to Int?

Generally i think all skills should have more different effects on several stats and skills, (elemental resistances or resistance to that same skill used by enemy), rather then just one, and that importance of attributes should be toned down a bit in balance.