Because there were less hispanics in the country in the 1980s. You can’t afford to “toss off” all Hispanic voters in the US. There are no more untapped pool of white evangelical voters to get.
Sure there are. They're called "Reagan Democrats", who are basically conservative on social positions. They got pissed off by the failure of the Republicans to properly pursue the war in Iraq and voted in droves for the "end of the war"---not because the war was "wrong", but because it was handled incompetently. They're also sometimes called "Jacksonians".
But I know what you really are---you're and "open borders" type who want so let the floodgates open for any and all Hispanics, legal or not.