Hydraulic disc brakes aren't really overkill on an e-bike, it's a safety thing. You really don't want to skimp out on stopping power when your heavy bike has a powerful motor.
Not for an e-bike it isn't. In fact, I'd say if you're not rocking hydraulic brakes on an e-bike, you're asking for a bad time. I know that most lower end e-bikes don't come with them standard, but to me, it's a necessary and immediate upgrade for safety.
Hydraulic disc brakes are not overkill with a bike of that mass [0] and power. Disc brakes are very common mountain bikes or any type where there is a lot of braking as caliper/rim brakes can overheat and pop the tires, so this unit should definitely have disc brakes. Hydraulic is better than cable/mechanical as hydraulic can generate more braking power, have better feel, and stay in better adjustment. The only downside vs cable+disc is cable is more repairable in the field.
[0] (overall specs indicate a lot of weight, Rivian are not proud enough of any lightweighting to even print the weight, and their autos are also very heavy, indicating a lack of lightweight engineering discipline in that shop which may carry over to their other mobility solutions)
I respectfully disagree. I've owned and ridden several ebikes with mechanical disc brakes. When they're properly adjusted they have just as much stopping power as hydraulics.
