Of course it'll improve, just like every other art form, there is always going to be someone to come out with something new that will set the bar of creativity higher. You can be an idiot and only look at pop music, but in reality there are tons of new creative bands and artists creating new genres and sub genres. A lot of 50's pop music is just as repetitive and boring as todays pop music but i've met many hypocrites who will disagree with that because they've glorified the past. Its pop, it was never sold to you with the promise of being unique or complex. Good music will always be out there, you just have to find it. Every good artist picks up tricks from other artists and learns from each other (for example: Rubber Soul influenced Pet Sounds, which then influenced Sgt. Pepper)
Music used to all be about art, guitars etc, having a message, and most importantly sounding good. Music nowadays is pretty much about selling out. Modern technology has made it possible to make music without any instruments. It has also made it worse. Most pop music doesn't even sound like music to me; it's so heavily computerized and with so many effects, it literally sounds like a speaker is broken. Broken speakers do not sound good. And even the stuff that isn't as heavily computerized is still heavily manufactured.
Case study: One Direction. Five boys with very good singing ability, put together by Simon Cowell. Theoretically, they should be good.
No. Their songs are so manufactured, it makes them sound painfully mediocre.
Case study 2: "Call Me Maybe." I hate that song with a burning passion. The first time I heard it, I thought I could puke. Then I heard people talk about how funny the music video is, and I thought surely that was the only reason people like the song. But apparently some people think it is a good song!
In short, music today is about selling, and I struggle to understand why it does.
But there is still good music being made. There are still awesome bands that play guitars and other actual instruments. But the sheeples who just listen to pop music have a tendency to label you 'emo' or 'hipster' if you listen to music that isn't pop.
Think about it this way, music today draws on music from the past. For example, sampling rock and roll and blues in hip hop, pop, dubstep and R&B. People who listen to this music today, give modern artists full credit for their work, not realizing that many of these songs are composed of music of the past. Aside from that, reliance on technology and digital media draws artists away from traditional methods of making music, and real instruments.
Music is not objectively improving over time because it is listened to by different people differently. For example, people born three hundred years ago would have different music taste than today. Even nowadays, people have different opinions about music. A person may like this song and another person may hate that same song.
While good music will always exist, "good" being defined as unique and creative whether enjoying immense popularity or not, it seems that a lot of pop music these days lacks creativity and is same-sounding. Just as we reward kindergartners for going to the bathroom, there seem to be accolades for any singing or music performance whether it is mediocre or stands apart as uniquely talented.
It is actually the reverse. Music has objectively gotten worse over time. And the odd thing is, science says it's gotten better. Our minds enjoy the ceaseless repetition that is today's pop music. However, there is still hope. The indie and underground scene continues to give hope and there has been noticeable signs of improvement recently.
New technology has made it even easier for untalented people to sound decent. Auto tuning vocals and placing them over music tracks other people have made is not hard. There is a vast abyss of mediocrity out there making it hard for music fans to find something good. Although, there have been some positive signs in very recent years.
200 years ago, you had to create a great music piece to be known. The shows were full of rich people, who were normally the only ones who received formal education, including arts. Today, when a label launches a single, this becomes automatically available to lots of people (in Internet, mainly young people), and it's success depends only on it's capacity to impress those people in a short time. The success of these not-at-all complex compositions makes the industry of the fine music unable to develop as it could in the past.