I liked the ridges, it gave them a more menacing look, and gave a slight distinctions between the Vulcans and the Romulans, without looking radically different.
Although it makes one wonder how the heck such a noticeable cranial evolutionary development happened in less than 2,000 years' time. The Vulcan Reformation and rebellion of those who went off to form the Romulan race happens barely two millennia before the TREK franchise. Hard to see how new skulls develop that quickly.
It's possible that Vulcan physiology is so different that their bodies adapt and evolve faster than that of Humans. I think it's possible that in only 2000 years on Romulus they evolved the head ridges. I mean just look how fast the Vulcans who went to Remus evolved into those grotesque beings.
There's absolutely no good reason why the Human/Earth evolutionary process has any basis on the evolutionary process of alien races.