I’m torn about them. On the one hand they free up the combat design to be as wildly different from the exploration as it wants. Which can result in really creative stuff. Favorite examples are Undertale, MegaMan Battle Network series, and Tales series.
But on the other they interrupt the flow of exploration, the music, you forget where you were by the end of combat and they can be very annoying if they happen to be common or just as you’re about to leave an area. The consolation prize of growing stronger with every battle only helps so much.
There’s nothing more annoying than chilling in ff 8 doing your own thing, then the loudest fucking music ever interrupts your fun time, ff 10 was awful about it too.
But other games it’s no problamo, I think the best way to do it is how the mother series went about it, with them being semi random and dodgable if you were good and didn’t want to do them.