Evolution not revolution.

Change is unavoidable and necessary, but ultimately it's impossible to know for certain what the end result of the change will be, the world is unpredictable a lot of time.
So any potential improvement is also a potential failure.
In politics a very high proportion of intended improvements are partial or complete failures.
It really is a lot safer for a country to change things little by little and deal with the comparatively small messes that causes, than to change everything all at once and be left with a giant mess.