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 personally don’t mind them, but I personally think the best kinds of random encounters are ones like pokemon randomizers where you step in the grass in a modded gen 3 game with every single pokemon in existence in it and it randomly pulls from the list of 1000+ mons in order to give you a feeling of true randomness in team building. Especially since you aren’t able to predict which creatures you will get.
Having a random table containing only a few different encounters isn’t anywhere near as fun and exciting as randomly having gods spawn as your enemy as a beginner in a randomized game followed by the weakest creatures in the game a moment later.
For sure, enemy variety is important.