BST's pets aren't affected because Call Beast is a JA.

And as far as I know, there is no JA that is directly influenced by skill level. There would be no way to incoporate a nerf without everyone suffering greatly (by having all JA influenced by skills)

or nerfing both good and bad BSTs in the process or killing BST completely. BST is already excluded from group play and removing it's incredible power to solo means the job could literally never be played at all.