Of course, change does happen but slowly in a lot of cases - as Max Planck famously said:
"A new scientific truth does not triumph by convincing its opponents and making them see the light, but rather because its opponents eventually die, and a new generation grows up that is familiar with it."
Academic "conservatism" hasn't prevented them from taking over the field as collected evidence made their correctness (compared to the old model) overwhelming, so that does not seem to be much of an argument against the existing system.