I do not mean to reduce tor to one-hop proxy. There is trade-off between speed and anonymous-preserving. For different user groups have different requirement of safety and anonymous, even one user's needs vary from different conditions he counters, sometimes he prefers speed and sometimes he needs more safety. My opinion is that to let people use their Tor more freely, for example, they can free to choose number of hops, they can choose a fixed exit node if they trust it, or they can let their Tor to choose path ramdomly or they specify a path they consider as reliable.There will be a lot of problems with one-hop circuit. For example, if "bad" people know that there are one-hop circuits in the Tor network, they will be more interested in attacking Tor, setting up more malicious nodes, etc., the consequence is a mess.