How are they not? Obama won by a margin of roughly 3 million votes, many of those young people who might be swayed by a policy change such as this.
Which is doubtful - it was the same excuse I remember when the centre left party in my country was voted back in. It had as much to do with substance as with the rhetoric - when the main leaders of your party are just plain mean and hating against LGBT, women, latinos, etc then it won't matter a single iota if you make a change in an area that has minimal impact when compared to issues such as abortion rights, gay marriage, immigration etc.
Except, as noted, that is the exact opposite of the original intent of the copyright laws in place in our constitution. Some how, over the years, "for limited times" has come to be interpreted as "the lifetime of the author + 70 years". Hardly what the framers of the constitution had in mind (the original term was 14 years and an optional 14 year extension).
You can thank Disney, Mickey Mouse and the Americana that is associated with it.