Your right it is…for any bike 100hp would be reasonable and still be very fast, but its a thing called competition
ex: Busa vs. ZX-14 they both don’t need the power they make, but every year they try to surpass each other. Only difference these days is manufactures of cruiser bikes are starting to make a shit ton of power as well, like the V-Rod. Cruisers are becoming lighter and being built with more power, plus the majority of them have simple bolt-on superchargers these days.