I'll explain. The problem is that you make the classic mistake people make in matters of economics, what Bastiat called the difference between what is seen and what is unseen. What is seen here: you have a ticket that allows you to board a ride in two minutes instead of a standby line of forty minutes. What is unseen: the use of fastpass is what makes the line forty minutes long, and without it, it might be half that. And unless you are able to get FP for every ride that uses it, your stand-by times will be affected.
If everyone were able to make equal use of FP, everyone's average wait would be the same as without FP. That's just the way the math works. When you factor in potential extra time spend getting the pass, walking back to use the pass, etc., it could even be a net increase in wait times.
Now, guests do not use FP equally. Some use it more and do actually benefit, some use it less, or not at all, and suffer. To the extent that anyone likes FP, they do so because they are in the first category, or believe that they are.
Which is fine, I guess. But you shouldn't say that FP is a system that improves things for all guests, because it doesn't. You should say that you like it because it's a game you think you can continue to win. Those of us who are against FP are people who would rather not play.
But there are many who visited WDW prior to the FP system, like myself, who believe that it is better. YOU may not agree, but unless you were around before FP , you don't really know what it was like.
I was there, I waited in the lines (or not) and I think FP has improved my experience. Others may disagree - but unless you waited in lines (and can really remember it) both before and after, you don't really know.