DNSSEC is the only truly hierarchical PKI with pervasive name constraints that we have. That makes it very valuable, even if it is difficult to leverage to solve other problems.
Like all PKIs, DNSSEC is vulnerable to authorities (that is, authoritative servers) acting as MITMs. WebPKI makes it very easy for nation states to acquire MITM credentials: just subvert a national CA and you're done because the WebPKI lacks name constraints. A real PKI makes this harder, because a nation state can only legally subvert authorities within its jurisdiction.
The root zone is special though, as long as there is only one, and that's why the root zone operators make such a special show of key signing events: to increase confidence that it has not been subverted. But the root zone is still a concern -- if not today, then tomorrow.
Enter QName minimization. By sending minimized queries -at the cost of having to do more queries, thus having higher latency- one can keep intermediate authorities from observing the full domainname that one is attempting to resolve. That makes is more difficult for authorities to MITM specific targets.