Kiwi had problems gripping anything but rope/pedi perches when we got him. I didn't think to do anything about it and just figured he'd get used to natural wood, as nature designed a parrot to live in trees, which are not always a sure-grip surface. Sure enough, he eventually found his sense of balance and his feet muscles got stronger and now he can climb around on any kind of perch with no issues. Even surprising slick and thin ones like the frame of his steel swing. I've never bought a single roll of vet wrap and Kiwi truly has about every type of perch out there between his cage, swing and play tree. He gets around in a most acrobatic way on all of them.
Barring medical issues like arthritis or injury, I think most birds just get weak feet from always having grippy surfaces to climb/sit on. I also think people stick within a narrow range of perch sizes based on species, when in reality, a parrot in nature would sit on everything from a very thin end of a branch to thick tree limbs. It's not just varied surfaces, it perches of many different sizes from very thin to very large that make healthy feet! I personally wouldn't do anything, except perhaps put some toys or treats out of reach to encourage your birds to walk on those surfaces and develop the skill to do so. It's what their feet are meant to do