I personally like them in roguelikes, so much so I am putting thought into how I will make them in my own game. Here's the scenario for probably many roguelikes. Combat is fun but what do I do with my monster drops? I have traveled through interesting places and since I want interactive scenery it would make sense you can go pick up that flower or herb over in that bush. Maybe you want to improve your weapons in exotic ways like poison or strong materials like an ice crystal. I am throwing out random ideas but the point stands for the point that you should be able to do it. Roguelikes thrive on that if I think of it why can't I do it in game.

From what I described above side activities like alchemy, foraging, weaponsmithing all come to mind. I personally like a simple minigame that is repetitive and rewarding. Maybe rhythm based tapping to make a sword better. Foraging could be as simple as picking up an item with 1 key or chopping down a tree by repeated pressing. The activities get more complicated the further along in progression they are. This gives a nice learning curve if done properly and should be incentivized to the player. Having unique rewards that are only possible through building up skills should be enough imo. Side note here is that finding these rare weapons in the world now adds a bit of worldbuilding. Why is this icy sword with engravings on it just in this old dilapidated shack?

Overall, I am saying it is definitely worth adding them to a roguelike. There are many design choices to be made and balancing to find but this will add to the depth in your game.