My research indicates that smart criminals tend to communicate in code. Because of the codes used and the frequency at which they change, the existence of communication is often of more probative value than the words used. Companies currently share this meta data with law enforcement.
If the veil of E2EE is lifted, smart criminals will move their communications elsewhere. They will find services owned by foreign companies in regimes that are not friendly to US law enforcement. Or they will move to low tech solutions that make collecting meta data more difficult.
Basically, I’m afraid that changing E2EE will catch criminals who make a myriad of mistakes that will get them caught anyways. Meanwhile, it will drive the intelligent criminals further underground, onto services owned and hosted in hostile (or less friendly) countries.