This is true, same with magic reduction. Unless I'm going to pick a fight with 3 giants or death overlords with ebony bows my armor rating is not that important as a melee fighter.
I have a character on expert and who since the 50s the only enemies that have given me any real fight have been those overlords with the ebony bows. Ancient dragons don't even bother me, the second they make the mistake of landing I rip them to shreds.
If you're playing with a dunmer, nord, or breton, magic resistance isn't that important because you can double enchant a shield with 45% of total magic resist, and if you use alteration, can get an additional 30% with perks. But with mage opponents just moving and dodging and closing the distance so you can power attack or shield bash and you can make quick work of most casters.