Jim,
Do you "need" a car that has more than 200 hp today--unless you're towing something probably not. It's all about want, and the driving experience. Fast acceleration within legal speed limits (or your personal limit) is fun--not as much fun as taking a corner at speed. But fun, nonetheless
If you think about it, you use every ounce of performance potential everytime you've floored the accelerator up to whatever speed you decide to lift. Trying to use a fraction of the car's handling ability is far more difficult to accomplish on the street. Yet, who here is the advocate for making Porsches handle worse because you don't need a car with handling capabilities that exceed the driver's ability to exploit them. Of course, one's not going to say that.
Once the HP and torque exceed the limits of the drive train/tires to put the power to the street, then I agree you don't need more and I personally don't want more at that point since I'm not real big into wheel spin and tire smoke.
In addition to making more money, that's why Porsche offers so many variants--want entry level power, hey we got a Boxster for you; want a bit more, Boxster S; want more but in coupe form, Cayman S; want more in a Cab form, 997; more--997S; more--997 S X51; more Turbo; more GT2; less GT but more of a pure 911 experience--GT3; want the most you can get, Carrera GT.
Choices--life is grand.
And yeah, I need a car just like what I have (PCA Club Coupe) even if I never hit the top end speed. Hello, my name is Paul and I'm a car nut.