Dem from CT has an excellent diary Medicare -- Why is it on the Table? The diary clearly explains the difference between Social Security (not in crisis, or fixed by raising the cap) and Medicare (more problematic because there is no cap).
I am convinced that in the near future something does need to be done about Medicare costs. But it is politically treacherous to do that before 2013.
The slightest hint of Dems changing SS or Medicare starts the Koch-brothers-funded wolves howling DEMS CUT MEDICARE. It worked perfectly in the 2010 elections "THEY CUT 500 BILLION FROM MEDICARE," even though it was based on the lie that the drug and Medicare Advantage savings were cuts.
They don't need truth -- any hint of cuts by Dems is pounced upon -- witness the recent memo after the debt ceiling deal that screamed "Obama put SS and Medicare on the table!"
It is a horrible truth that any modification, no matter how thoughtful, of SS or Medicare by Dems is trumpeted as cuts and death panels, while the obvious intention of Republicans is to kill the programs completely. When that intention is disclosed, e.g., by the Ryan Plan, voters react strongly.
What to do? Essentially, nothing until 2013.
1. SS is not in trouble. Nothing should be done until 2013 at the earliest.
2. Similarly, although Medicare is threatened by cost increases, any reforms are politically lethal and may negate the political advantages Dems received from the Ryan Plan.
So even though Dems want to be "adults" and deal realistically with Medicare cost increases, they cannot afford to do so until 2013 at the earliest.