Obama's underlying reason for non-enforcement of immigration laws among other reasons is that he fully supports a North American Union. He wants us to be like a EuroZone with open borders between Canada and Mexico. He is just pushing and pushing the envelope toward that goal. Otherwise, living in AZ like I do, I would describe his behavior as incomprehensible - but he knows exactly what he's about.
On the issue of carrying "papers," unless it has been revoked, I thought all noncitizens living in the US had to carry immigration papers "on their person" as a matter of course. Therefore, I find nothing onerous in our SB1070 allowing law enforcement officers during a probable cause stop to ask for ID.