They're faster than the stovetop by a lot over here, so if you're boiling a lot of water multiple times a day (for tea, coffee, ramen, and whatever else) they're super convenient.
If you're not making many hot drinks (or have better machines for that) I'm not sure how much use they are.
As for cooking, I know for myself, when I make something like rice, I boil the water in kettle first, and it definitely saves me a couple minutes. A few minutes doesn't sound like much, but it all adds up. Another commenter says that they're actually not that much slower over there, so it might be worth timing one compared to stove top?
I think they start on 0 here though. Reddit automatically upvotes your own posts, but not here