They can tap phones, and should be able to tap phones, along with VoIP, video calls, and mail. But while privacy isn't absolute, their ability to wiretap communications with a court order has never been absolute either, merely opportunistic.
These are opportunities they don't have available to them, and it needs to stay that way.
They should not be permitted to set aside all other concerns just to keep that wiretap and search ability in the cases where it comes up, because it simply isn't that important compared to all of the problems they will cause in the process.
People, including whistleblowers and political dissidents, even in the U.S., will be harassed, threatened, blackmailed, or even killed as a result of their tampering, and the government itself will misuse those expanded access powers, just like all the others they've publicly or secretly obtained.