It quickly came to mean, to deplore or to disapprove in an especially morally laden way.
I disapprove of what you say, but I will defend to the death your right to say it.
So why do we still love her but disapprove of all things GOOP?
late 15c., "disprove;" as the reverse of approve it is first attested 1640s. See dis- + approve. Related: Disapproved; disapproving.