Something like this happened on the planet Urk where orks were fighting eachother for thousands of years but had no desire to ever leave until Ghazkull united them, but then they constructed spaceships with no problem. There's also a lot of feral orks in 40K universe while it shouldn't be the case since mek knowledge is genetic. So it indeed might be the safety switch made by the Old Ones to reduce the danger of Krorks. And both after Horus Heresy aftermatch seen a lot of galaxy unified under the Imperium and now when the overal danger level in galaxy intensified greatly the Ork activity also greatly risen which given birth to a Beast (M32) which was almost a Krork and now Ghazkull is on a good way to becoming one, so it might indeed be correct to say that the Orks are adapting to the level of danger.

The book "Da Gobbo rides again" provided some interesting lore parts about how greenskin specialisation works.