The problem with dielectric strenght is that it´s a very destructive test. In Brazil, we are changing the routine tests required. We´ll begin using IEC 62353, which uses insulation resistance testing in place of the hipot test. Insulation resistance also measure the quality of the insulatio nbarriers, but does not damage the equipment.
You might use a rationale of this kind for justifying not implementing routine dielectric strenght testing, and then ask what your notified body thinks about it.