I'm no fan of DACA but the Republicans brought it on themselves by fighting every single thing Obama did regardless of whether they personally agreed with it or not. .
I understand your point, but that's not really what happened. Don't forget that Obama and the Democrats could have passes a law outlawing Republicans if they wanted to do so. Obama and the Democrats in Congress had two years to pass anything they wanted to pass. They could have passed any immigration laws they wanted.
Ironically, and this is easily verified, the Dems could have gotten almost everything they wanted in Immigration Reform with President Bush. Bush wanted to reform Immigration. Know who stood in his way? Pelosi. As referenced by your first sentence, Pelosi stated publicly, in print no less, in a Time magazine article that she instructed every Democrat in the House to oppose everything President Bush supports. http://i63.tinypic.com/augxn9.png The Democrats didn't want to solve the issue. They would rather have the issue as a political club.