Consider this: If encryption is suddenly turned off for all communications, and police have access to all of it via warrants, that's like getting a warrant for every home in the US. Obviously if the police had a perpetual warrant to your home, you wouldn't want that, why is it reasonable they have one to your data?
And it has been proven many times that not only will the access be abused, the secret backdoor will not remain secret and now every unscrupulous person can potentially have the same access.
