Your concern of the internal problems of Mexico is not displaced, but its focus is. We do not have the luxury of waiting for the social, political, and economic conditions in Mexico to improve before we try to reform our immigration policies.
I don't think waiting will do any good. Mexico has been poorly governed since independence. I don't know what the solution is, but as long as the Mexican ruling class can get away with ripping off its citizens there's no motivation to change a thing.
I'm not as pessimistic about it as you are --- for one Mexico is a very very wealthy country --- but most of the vast wealth is cut off from the majority of it's citizens. Most cannot even make ends meet --- but yet they were doing that a generation ago. Mexican farmers used to be self-sufficient substinence farmers not long ago--- now they are landless peasants who have seen their irrigation waters cut off and their farms dry up. They were kept down by their own government which would not allow them to have tractors --- then it turns around and says they must compete with American farmers who do have tractors --- and they cannot compete so are forced to give up farming. Incredible that the people who developed corn now must import it.