They're great for minimizing oxidation along cuts. E.g. cutting iceberg lettuce and avoiding having the edges turn brown. They're also very lightweight, which is nice for some things, while being bad for others. I'd never use them the way I do my workhorse chef's knife, but there are certainly tasks I prefer them for. Dicing lots of hot peppers comes to mind, oddly enough, as does some very precise and relatively tedious knifework like making very even matchstick cuts for carrots/radishes/etc (the large one has a very wide blade, which is great for this, and is lightweight enough to reduce fatigue).
Overall, I can see why folks like them. It's not really the "no need to sharpen" point. It's more the "lightweight and very thin" part, along with a non-oxidizing edge.
I'm still kind of opposed on principle, I suppose, but I do use the set we were gifted fairly often, despite having some very nice steel cutlery that I'm very fond of. I can't blame anyone for buying them now that they're priced more reasonably than they used to be.