I agree its probably not much of a problem. However it is somewhat different than the paper process. You actually had to be there to get the paper fast passes and you could give them to others if you decided not to use them. Now I can choose fast passes from my mobile phone 1200 miles away from the parks. Granted if I cancel them, they could be put back in the potential pool but if not, then they are lost just like paper copies not handed off to others.
Like I said, I don't see a real problem here. I don't think any significant amount of people are douchy enough to purposly reserve fast passes they aren't going to use but I just thought the issue was interesting to think about.
I would be interested to know how the percentage of unused fast passes compares under the new system to the old system. Of course I don't even think disney could compute that as I can't imagine they compared the number of paper fastpasses turned in to the number generated.
Overall we enjoyed using FP+ on our last trip and it will be intersting to see how the system evolves going forward. I like that they are aleady making some tweaks based on user input. That is a good sign.