Had Bitcoin not being designed this way, it would have been killed by a different kind of 51% attack in its early days, Bitcoin doesn't only need to face threats of governments, but also that from botnet operators, random script kiddles etc. In fact, that we are dealing with government pressure itself is evidence enough that the system worked. Also, 51% attackers can follow you wherever you go, however many times have hard-fork.
So you have 2, 3, maybe 4 hard-forks which brought the attackers exactly nothing. How many more times would they then try after that? "Dude, stop trying to hit that ghost with your sword. It went clean through doing nothing the last 5 times!" - "Maybe if I swing extra hard next time."