Call me out of the loop, but I honestly don't know. Do video games have music soundtracks the way movies do? If not, why not? Do you think there would be a market for that?
They most definitely do! I am actually a video game soundtrack aficionado. There are so many great ones. For example, Cuphead has an excellent soundtrack based on early 20th century American style cartoon music. Highly recommend you check it out.
There were several Kingdom Hearts and Final Fantasy-themed concerts in the past, and the tickets got sold out rather quickly as far as I know. I'm not sure how successful the sales were for the soundtracks alone, but the franchises were highly popular to warrant their own concerts.
I haven't heard of anything like that recently. I wonder if it means that the quality of game music has decreased over the years.
The cut scenes in the games needed music or else the scene will just be so dry. Even Super Mario has its own soundtrack. When you hear that famous opening music Mario, it will immediately register on your mind a little man with the red cap running and jumping in a one-way street.