That might all be true, but I cannot begrudge someone if they decide to use their talent to make more money. It's obvious that Phil Collins said to himself in the 80s, "I want to make a lot of money," and he did so by writing songs towards that end. Is that right or wrong? The answer: neither.
If you use your talent to make money, the music won't be nearly as good as if you used your talent to make music. I've only heard a couple of Phil Collins' songs from the 80s and I know I don't need to hear any more of his songs. It doesn't arouse my interest in the least.
There isn't right or wrong. The artist can do whatever he wants. But if he decides that money is more important, then the music becomes of secondary importance. Then originality and creativity get thrown out of the window and you become poppier to appeal to the taste of the masses, creating a product strictly to sell. That's what most artists do, unfortunately. And all for the sake of money. It is not right nor wrong, it is up to the artist.
In some cases it is about money, but that isn't what it is necessarily about.
For some reason, we think, "Sure, an artists simplifies his music, sells out, puts out crappy pop music and makes a lot of money." What's not understood, is that simply putting out pop-sounding music is no guarantee of popularity and a lot of money. Actually putting out material that captures a large audience is an achievement, and something that not a lot of people can say that they did. Think about artists that tried to get more poppy and capture that audience and fell flat. I'm willing to bet that the failures are more common than the successes.
Second of all, artists like to set challenges for themselves and push their limits for the most part.
Since we have been talking about Phil, think about his career and what he did. Was a part of a huge and legendary progressive rock band that was very successful (even before the 80s hits of Genesis), was a part of Brand X and that scene, and put out some interesting music in his first two solo albums. Sure, there was some pop influence in those solo albums, but it didn't dominate the way No Jacket did. So where does he go from there? Rehash what he has done in his career? Duke pt. 2? Instead he goes for something different, and something difficult. Think about it, a drummer and singer from a progressive rock giant puts out a huge pop album and becomes a cultural figure of the decade. It's a lot easier to say than it sounds. Imagine if for Petrucci's next solo album, he decided to go full-on pop, the album blew up, and suddenly you were hearing his songs everywhere, non-stop. Bizarre!
And we have to face it, becoming popular is a goal of a lot of bands out there. If it were really all about the creation of music and nothing else, everyone would just spend time in the studio writing and doing nothing else. People release music for other people to listen to it. How many bands say, "We want to become the biggest band in the world?" How many bands say, "We'd really like to play clubs of 100 people for the next 30 years?"