I don't think it ever was the _highest_ good. It may be argued that it has moved around the hierarchy, and it may in fact not be at an all time high, but there were always things which we (society) put above liberty.
I always thought of personal liberty as the value from which other values derive. For example, the law exists to protect our rights (the right to life and the right to property being the most obvious examples) from bad actors. Social welfare and socialised healthcare restrict the damage that personal catastrophe and random chance can do to our freedoms.