If you have a logo that you worked hard on for your brand of music, then it can be advantageous on your end to trademark it.
The reason for this is, not just that it can provide you with additional source of income but also, it can serve as protection too.
It Keeps You in Play
Yet another reason to own your trademark is when singing to a record label. Assuming that at some point of your career and it is dwindling, which can happen to anyone, the label has no bearing in putting you out of the game and make money without your permission. Mind you, this had happened many times before.
Not like when you own a trademark. The label will be forced legally to come to you in licensing the logo before they can start selling or promoting the album.
Trademark is Good!
Another known reason to trademark is for merch or merchandise. In the event that you have established massive fan base that your name has value to it, you can put it on your merchandises and sell it for additional stream of income. You can put it on t-shirts and sell it outside of your gig for fans to show support of your band.