But still, by no means, half steps between the notes were equal. With Meantone tuning all the black keys which has two names would sound differently. In eighteenth century, enough people evoled back to Homo sapiens and as music was getting more complicated, musicians realized the need for equal half steps on the scale so that one could write music with more accidentals and also modulate to any of the twelve keys at any time. With equal temperament he didn't have to tune the keyboard every time he played music in different keys. From this mement on, musicians were doomed to suffer from newly composed music more complicated than previous times such as music of twelve different keys in a single measure.
Music gets more and more complecated just like biological evolution.
For sure, it doesn't mean music got worse as some people refer to contemporary music. Believe it or not, people didn't even use thumbs to play keyboard at one point. A tone is produced by any substance that is vibrating at a certain frequency. In Baroque period standard pitch was lot lower than present almost a half step below. Many orchestra in the different part of the world have their unique standard pitch sometimes higher or sometimes lower than 440 Hz.