I've consistently heard from conservatives about how Obama should have been more of a 'uniter' and shown more 'leadership' but they are always completely unable to articulate what exactly they wanted him to do differently. (other than simply pass Republican policies into law)
When people talk about Clinton working across the aisle they completely miss the radicalization of the Republican Party over the last 15 or so years. Notice how the Democrats have barely moved, but the Republicans have gone through the roof.
Republican radicalization has let do unparalleled polarization:
In short it was much easier for previous presidents to work across the aisle because there was actually considerable overlap between the parties. In previous years quite a few conservative Democrats were more conservative than more liberal Republicans but this is no longer the case:
People who point to Clinton and say he worked across the aisle and that Obama should emulate him miss the fact that the 'radicals' Clinton was fighting against were people like John Boehner, the man who was recently outsted from his position for being way too moderate.