As much as I personally like the Bushes, their name was a massive turnoff to the average GOP voter. From H.W Bush getting beat by Clinton to 2008-2009 with Dubya and the War on Terror. These factors would contribute to independents and moderate Republicans abstaining or defecting to the Obama camp. Romney wasn't a Bush but he wasn't a great candidate. A better Republican would've done better but a Bush would've done worse than Romney 2012.
Him being on a ticket would have been political suicide too.
