What would trigger the less developed eyes to be a trait that would be passed on to future generations? How cold losing a sense increase the chances of survival and passing on the trait of loss?
The same thing that triggers a change that is more developed. A mutation.
<How cold losing a sense increase the chances of survival and passing on the trait of loss?
1. You are assuming that evolution would always be a change that increases survivability. A species could evolve in such a way that it becomes extinct or, perhaps, just not quite as survivable.
2. The loss of a sense could be paired with an increase in other senses that are more applicable to that species, or at least more useful at one point in time (see number 1 above).
3. It has presumably occurred already. See, for instance, Astyanax fasciatus.
Biologists have a penchant for making assumptions that are not demonstrable or realistically testable. Assuming cause and effect, or worse, confusing cause for effect can lead to bizarre and wholly incorrect conclusions. Could it have been that astyanax fasciatus went blind and those living in the caves survived because eyesight wasn't necessary? How could you even test that?
Just like philosophies, religions, cultures, ethnic groups, etc., have memes, so does biology. After reading Hawking's latest (and ridiculous) screed, you can see that scientism has now been provided with its own metanarrative (string theory, which, according to Hawking, should be embraced as fervently as the "fact" of anthropogenic global warming). It even includes its own eschatology. I will grant that the completion of this metanarrative was penned by a physicist and not a biologist. I just don't see the difference in what the evolutionary biologists and string theorists are providing me and what the Hindus tell me. If you can't prove it in a repeatable test, it's not science. It's philosophy. I have nothing wrong with philosophy, but call it philosophical biology or philosophical physics, not science.