The central argument, right or wrong, against any reform is that it will make the US more vulnerable to terrorist attacks in the future.

If you accept the argument that our drone program, as it is being used, is diminishing the strength of terrorists and thereby makes our country safer from their attacks, then you are a holder of the mindset which allows constant expansion of our military's lethal reach, often in secret and without accountability of its leaders, possible. I think it is a profoundly mistaken view that our drone policies will create any greater peaceful stability anywhere in the world that they are used to enforce secret death panel decisions by our leader, the one who has numerous times by now sworn to uphold and defend the Constitution. 

And this ultimately will put American interests and lives at stake.

It is not clear whether you are saying this last sentence is part of the CIA's argument or that it is your conclusion. Of course the secret, unelected CIA will justify their killing just like the our leaders will and both tell us to just trust them. Obama says this even if his recent actions indicate that he doesn't think we will be able to trust the next elected President to secretly kill secretly convicted people based on secret evidence. The next President will need some established guidelines, he says. What is to keep the next President from saying screw you Obama, you set your limits and I will set mine. We both agree, screw the Constitution.

Politicians, including Obama, are not going to make sweeping changes that open them up to accusations they are weak on terrorists and willing to make the US more vulnerable to attacks.

This is correct, so those people who think the policy is wrong must attempt to change the calculations of the politicians as to what gets a vote. That, or keep our reasons updated on why to vote for the presumed lesser evil again next time around.