Carter and Clinton overdo it to the point of being intrusive, especially Carter. But W hasn't been completely silent. He has popped up two or three times to insult the base concerning their objections to amnesty, and a few months back his remarks concerning "the isms" that come up from time to time.
But not a word from W as Obama throws away most all possibility that any good will come from all the US has invested in Iraq and Afghanistan. At least Cheney had a few relevant things to say recently.
W tried to pass amensty too.
I remember the protests and anger on FR