My Brompton has fenders. Getting the fenders was the easiest way to get the rack with wheels. (The wheeled rack with fenders is an option when you order the bike. And I'm all for easy.) The wheeled rack lets you move the bike easily when it's folded. It also becomes a stable bike stand for the partially folded bike.
It turns out, fenders can be handy. This week I got caught in not one, not two, but three downpours on a single ride. The neighborhood roads I was on quickly turned into shallow lakes. I picked my way around the worst spots, but I had to ride through a lot of water.
On my other (fenderless) bikes, my kit would have been splattered with road filth. But all the water that got to me was rain coming from above. I was soaking wet when I got home. But that was it. Wet. No filthy stuff all over my legs or back.
Fenders do look quaint. But maybe, just maybe, I'm going to learn to love them.