I agree with this, but even if it comes down to $0.01 a piece, it doesn't change one fact : it's not free anymore. The next question is : what is the limit for an acceptable price ? a nickel, a dime, a buck, a fiver ... there is no end to this, because once the process is set in motion, there is no stopping it.
FP are supposed to be free, they've always been free. There is a line, and once the guest crosses that line, or for instance when the guest begins to accept to pay, even a lousy cent, for a Fastpass, then the road is paved for Disney to sell FP+
Most people will argue that $0.01 is nothing, and as you just did, many people will argue that it's rather cheap compared to what guests usually spend for their disney fix. But a line has been crossed here. Guests have proven that, as long as the price seemed "low" or "reasonable", they're ready to pay. Now the only thing Disney has to do is to make FP+ very worth paying for, and as a result, the price can be higher, guests will be happy to pay.
It might seem cheap now, but no matter how cheap it is, it's still paying for something that's supposed to be free. And paying for somthing that's free is always too expensive, be it only 1 cent.