Even people who typically carry water for Democrats understood this was a bad idea -- for example, Linda Greenhouse of the New York Times:
So let's tote up the damage:
This time, Justice Alito shook his head as if to rebut the president’s characterization of the Citizens United decision, and seemed to mouth the words “not true.” Indeed, Mr. Obama’s description of the holding of the case was imprecise. He said the court had “reversed a century of law.”
The law that Congress enacted in the populist days of the early 20th century prohibited direct corporate contributions to political campaigns. That law was not at issue in the Citizens United case, and is still on the books. Rather, the court struck down a more complicated statute that barred corporations and unions from spending money directly from their treasuries — as opposed to their political action committees — on television advertising to urge a vote for or against a federal candidate in the period immediately before the election. It is true, though, that the majority wrote so broadly about corporate free speech rights as to call into question other limitations as well — although not necessarily the existing ban on direct contributions.
1) He insults a coequal branch of government (the judiciary) in the home of another coequal branch (the legislature), drawing the quiet ire of a Justice who will be in position long after the President has returned to Hyde Park;
2) He gets the facts of the case wrong; and
3) He complicates the life of Elena Kagan, his Solicitor General, to score a cheap point.
As we've all learned, President Obama has a lot to learn. Here's yet another suggestion that I'm certain the President will not accept, but I offer it anyway. Every administration engages in some measure of demagoguery, but smart administrations job out the demagoguery to underlings. Let Axelrod to this stuff, Mr. President -- it diminishes your office.