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.
Oh yeah, Undertale is gnar. They actually did something new and different with the style, which is what I’m really about here. Octopath Traveller is another good one; the thing that it has going for it is the sheer number of options you actually have. It’s not just “attack, item, magic, defend, or run away.” It also has a lot of other Western RPG elements in it like actually having dialogue choices that matter making it an actual game with branching paths and not simply a story with some minimal interactive elements.