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.
I’m in the “if I can’t avoid them, I’m not playing the game long” camp.
I don’t hate them, and they can be fun. But most of the games that do them make them impossible to bypass. Like others have already said, when you’re questing, they just derail the gameplay experience. There’s times that’s okay, but if a game has them often enough, it ends up making me hate the game and quit.
It’s why I don’t go back an replay the final fantasy stuff.