Well, first of all, there was an overwhelming popular dissent with the decisions of the Eastern European governments, as the people wanted nothing with the missile defences. And as a matter of fact, Eastern Europe is now safer, as Russia no longer has to aim its own atomics at the little nations that would rather mind their own business and prosper than live with the thought of megatons of fusionable material aimed at them.

Why would those nations seek to be involved in a global power-game? Sure, for an American, a conservative one especially, this seems to be tantamount to giving up, kneeling before Russia. But while Americans are safe in their relatively isolated continent, the European states will suffer the worst, in the case of war, which is what the missile shield is designed for. Diplomacy is all about giving up some things while gaining others. This is not such a splendid time for an arms race. In my thinking, the "Eastern and Central European Allies" are more likely to be relieved than upset.

Finally, from what the BBC News wrote, it seems the missile system merely detonates the warheads hurtling towards a target, instead of disabling them. Basically, just an explosion in a different place. But in what place? Above the territory of the Central Europe?

Leaves America more vulnerable to the emerging nuclear threat from Iran and North Korea, and
...And if the missiles are designed to protect against Iran or DPRK(which is utter rubbish), then would it not be logical to place them in Iraq, Israel, Turkey or such to protect again Iran, and in Japan to cover DPRK? I honestly have no idea what Mr. Bush's plan was when he placed those missiles there, to enrage Russia. I see no other purpose. What is the gain?

green light to Russian aggression and interference in the region
I fail to see how Russians can exert aggression and interference on NATO and EU states. Other than the usual natural gas-blackmail. I am beginning to be concerned with the credibility of the OP's sources... Honestly, that statement is downright farcical.