An ebike can be for both pleasure and exercise. Most ebikes are pedelecs - you're still cycling, you're just getting a boost. They aren't loud, you just either get somewhere faster or with less effort. I find an ebike to be more pleasurable than a regular bike 90% of the time.

Just because you're doing less work, doesn't mean you're doing no work. An ebike can provide mobility for people who aren't in perfect shape. Ebikes can also allow you to use your bike for more errands, like getting groceries that people would otherwise not do on a regular bike.