bipartisan commissions

In the current issue of the Economist, Wisconsin Representative lauds the paper's analysis of America's long term deficit problem. But he bristled at their suggestion for a bipartisan commission to reform taxes and entitlements. From that analysis:

One way to finesse these toxic politics would be to establish a bipartisan commission to fix entitlements and taxes, as proposed by Kent Conrad and Judd Gregg, respectively the most senior Democrat and Republican on the Senate Budget Committee. Its membership would be drawn from both parties, both chambers of Congress and the White House. Democrats and Republicans alike would have to make sacrifices. To preserve this grand bargain, Congress would be allowed only to approve or reject the commission’s proposal, not amend it.

And Ryan's complaint:

Yet your reluctant conclusion to outsource the tough decisions to a commission fell short. Contrary to popular belief, politicians are elected to solve problems, not punt on them. Americans should be treated like adults and offered bold solutions, as I’ve done with my comprehensive entitlement-reform proposal, “A Roadmap for America’s Future”, which tackles overdue reforms to Social Security, health care, the tax code and our broken budget process. Pessimism with our political process is understandable, but the United States has faced more difficult challenges in the past.

I don't understand how this would be 'punting' any problems. The entire Congress would have to vote on the thing. This no amendment, up/down vote commission tactic has been used successfully before (Social Security crisis in the early eighties). Matt Yglesias thinks it's a dumb idea, but I'm not sure why this sort of thing isn't used more often. It seems to be proposed for crises, where congress folk all want to pass something important and prevent the usual gaming among their peers. A smaller number of more focused (and perhaps more specialized) brains hash out their differences and then the whole Congress votes on the resulting bill. Why not, for instance, set up a bipartisan commission on effective greenhouse gas emissions reduction strategies. Even if you still didn't get a carbon tax out of that (because the whole Congress might not want to vote for a big tax increase), a cap'n'trade scheme resulting from such a commission might actually be efficient, and less riddled with industry favors.

I'm probably naive, but I like mechanisms for removing trash from legislation. I was always fond of the idea of a presidential line-item veto too.