Government can compel servers in its jurisdiction to use a mandated CA. DNS would nicely compartmentalize it to the zone controlled by that government as opposed to the CA system where every random eMudhra CA has infinite reach.

Not that it isn't an interesting question but what's preventing them now? You can get a certificate for any domain you control. It is just really obvious if you abuse that power. Which shouldn't really change with DNSSEC I think.