DNSSEC was designed around real world constraints, not the mythical world where every resolver can talk to authoritative servers directly or only through trusted recursive servers. Yes, there are ISP that force you to use their name servers.
DNSSEC is designed to cope with untrusted authoritative servers. Most people don't have the resources to provide the servers necessary for fault tolerance. With DNSCurve you have to trust those operators to not change the data as any change they make can go undetected. With DNSSEC the worst they can do is reduce the effective number of name servers for the zone.
As for OpenDNS you still have to establish a trusted path to them.