Maybe the airlines figured that it was not profitable to have a route like that since most of the passengers are leisure-travelers and therefore would be flying on discounted fares.

I too would like to see a non-stop from the West Coast to ACA. However, I don't think that is going to happen anytime soon. Plus, I think a lot of people would prefer to fly to Hawaii instead of Mexico just because Hawaii has a more "exotic" flavor to it.