Obamacare is not hypothetical
It is the law of the land. Changes to Obamacare are not restorations of the natural order, they are deviations from the status quo.
When Romney says he will not "cut" Medicare he is not saying that he will not cut Medicare, he is saying that he plans to add $716 billion to Medicare costs, without helping any Medicare beneficiary in the process, and to thereby make Medicare insolvent during his first term.
ADD. In addition to. On top of.
When you add spending to existing law (which Obamacare is) that is NEW Spending. Romney proposes NEW Medicare spending that does not benefit Medicare beneficiaries (it goes only to doctors and private insurance companies, both big GOP donors), and which there is, in fact, no money to pay for.
A candidate for President is proposing the better part of a trillion dollars in new spending, specifically to be wasted on things that candidate himself has said as recently as April are unnecessary.
And this is only so a candiate can try (desperately) to paint himself as a defender of Medicare... a program the entire elimination of which be publically supported mere months ago... a program his just picked VP candidate, and every single member of his Party in the House, seeks to eliminate.
No Democrat has ever proposed such an absurd waste of money. It truly is the most ridiculous spending proposal ever.
(And also possibly the most multi-layered fraud in a century of American politics.)