Music doesn't only changes people´s mood. It goes beyond that, Music reflects society on a much deeper level because it mirrors the attitudes of its time. Society is constantly changing and the world we live in today is very different that 50 years ago, this is the reason of why music has changed a lot through time.
For example, the 1950's were a very optimistic almost fairy tale period because
wars were left behind and peace was coming again, and the music typically reflected this.
The 60`s was a decade the decade of the rebellion of the youth, something that wasn't seen before. Music in the ’60s was a way to rebel not just against the music of a previous generation, but against war and the government. It also searched for equality and peace.
The music nowadays has changed a lot since the gold ages of Rock and has experienced many changes, it has been transformed into something less “organic” by this we mean that it's too digital, that is understandable because of the great development of technology but there are still great artists that found a way to fusion the digital music with traditional instruments creating a new sounds and effects never heard before.
By the other side Popularity and financial success is more and more used as the barometer to judge talent and artistic success. How well an artist works with the social media game will impact more their career than making a good song. The art of writing a memorable song has taken a back seat to performance and image.
There has been a massive development in “commercial music” making it to much about the profit and less about what the song is trying to express, making everything perfectly fit to sell to the masses but the actual meaning of the song makes no sense or centres in stereotypes that little by little are being adopted by society and lead to massive consumism and intolerant people.
Finally, music has been and will always be a very important way to express ourselves. Even though it has suffered a lot of changes,throughout decades because of new tendencies and new things and genres that become popular.