What do you mean "becomes"? J. Edgar Hoover actually did use his power to persecute political dissidents. I say this whole FBI backdoor/legal intercept thing reeks of trying to do that sort of thing again.
I mean, it's pretty easy to monitor Quaker anti-war activists: they do everything publically and invite participation politely. No agency needs wiretap access to monitor them. So, who are they going to monitor with this?
This is the real danger of letting government become too powerful: individuals within it can abuse that power.
If your political or religious views are or become unpopular, how much power to monitor, control and punish you do you want government organizations to have? How much oversight do you want for them?
I mean, it's pretty easy to monitor Quaker anti-war activists: they do everything publically and invite participation politely. No agency needs wiretap access to monitor them. So, who are they going to monitor with this?