If the planet Vulcan experienced numerous atomic wars then perhaps the ridges are common to Vulcanoids in general and it was the Vulcans who stayed behind who mutated and lost their ridges. This might also explain why Spock and other Vulcans have a high resistance to radiation, the Vulcans with low resistance did live long enough to reproduce.Who knows why they have ridges. There could have been mutation from atomic wars, genetic predisposition or interstellar travel.
Three thousand years is a long time to remain a high technology civilization. If the Vulcan had a series of large non-atomic wars every few centuries, then they might have periodically lost the technology to achieve warp flight, perhaps even space flight. The Vulcans at the P'Jem monastery could have been marooned for decades or centuries on occasion. Also later, under the teachings of Surak, the Vulcan could have turned inward culturally, the lack of the need to explore on Vulcans parts that we saw in Enterprise (from T'Pol) easily could be philosophical aspect of their "new" culture, rather than part of Vulcans natural physiological make up.


That they didn't have warp travel until later? I don't see why that's at all necessary or even useful, because of the terrible problems it brings up--principally, the Romulans being an unknown force in the 2100s and only slightly more known in the 2200s. A thousand years might be what it took to get back to the same economic levels, sure, because of the loss of population from war and exodus and the homogenization of their society afterwards, but giving the Vulcans warp around the time of Jesus presents major issues.
)
.
That's not a good reasoning. We don't know anything about Cochrane's background before April 2063. For all we know, he was a graduate school working on warp theory at an ivy league school when the war started.
), decided to do a manned mission instead of an automated test run.