Hey Saurik, long time fan! (since the jailbreaking days)
I actually talked to some of the Tor folks about this, and it seems like it mostly boils down to their chosen trust model and the fact that anyone can be a Tor node.
Most of the two-hop designs have fixed hops, and admittedly they can't beat Tor w/re privacy by any means. The fixed hops can however offer better reliability and latency.