It would price innovation out of the market.
Also, not sure what you mean by weak encryption. An average attacker now has access to decrypting tools out of the box (with a few Linux distros) so wep isn't stopping anyone really. Even noobs can be trained to crack with an hour of youtube.
I realize this is likely not your argument but the only thing that does is delay the access to data, not prevent it.
Private keys will eventually leak, if not publicly, through nation state espionage.
Weak encryption prevents the average attacker today but not the average attacker in the future.