My response is that this is a political maneuver on the part of the Republicans and not a serious offer. It is meant to show the public that the Republicans are willing to compromise, only to have the Democrats reject their offer.
I say this because the Democrats insist that some taxes must be raised to help reduce the deficit. This proposal does raise the amount of money that would come in via taxes, but then it simultaneously makes the Bush tax cuts permanent so that the overall effect is to reduce taxes.
So, the Republicans could not seriously have thought the Democrats would agree to this. Therefore, it was a proposal made for political purposes only.