We don't wish to take powers away from any state, the purpose of amendment is just that. So the states (citizens in them), are the ones with the power, NOT activist judges.
Then there is absolutely no need for the amendment. The citizens of every state have it in their power to amend their constitutions to protect marriage. That is exactly what the citizens of Massachusetts are going to do this Summer. The federal government has no business stepping into state affairs, including state judiciaries.