I have feeling that they had gathered database with usernames and passwords, cause only certian sites were targeted to use mitm, mostly it was mail services like gmail and social networks, facebook, youtube and others. Other sites were working fine even without that cert.

And after that mitm they had to stop, due to people's discontent and lawsuits. These are also reputational losses, it is unlikely that foreign companies will want to do business in a country in which personal data treated this way and where government wants to see all your passwords from email services and bank accounts.

There was also a question about ensuring the security of a root certificate that can decrypt data, it could easily get to third parties who could use it for their own purposes.