Kanth and Toad, I understand yer positions. Europeans shouldn't have political say in how the US taxes its citizens or runs its economy.
That is not to say that they shouldn't be interested. We're talking about the largest economy in the world, and the most powerful nation on earth. If their training and experience make them think it's a bad idea, due to the positions of power they have, they have an obligation to voice their concerns.
They might indirectly affect US politics by giving opponents of Bush's suggestion some ammo. This could be part of the objective, but I doubt these chaps would say what they say without being genuinely worried.
And I think it should be seen as a word of caution, not as meddling in the internal affairs of the US. So there's no need to be angry at Europeans over this; the US comments on other nations and rarely intervene themselves. Everyone does it - it's just how the world is today.