People, the bottom line is this - FastPass tickets were created as a benefit to the guests to avoid extended wait periods on certain attractions.
actually, that is the secondary reason. The primary reason is that Disney realized that guests who are standing in line can't spend money, and the longer the lines the less money they will spend. After all, it only positive affects FP holders. Guests in the standby may or may not actually be benefitting at all.
The time printed on your FastPass is a lot more important than you think. It is there to allocate tickets appropriately, in order to ensure FastPass lines don't get backed up with 200-300 people at a time.
This is true. FP is a crowd re-distribution tool. In theory, the people obtaining a FP would have gotten in line at that moment instead of getting the FP. Now they are relegated to a time later in the day (taking the spots of people who got FP during that hour who will in turn go later, and so on). An attraction's allotment is proportional to its hourly capacity, so in theory the allotment shouldn't technically affect the standby line (i.e., if FP didn't exist then theoretically the wait time will be the same).
The problem is that theories rarely ever come out 100%. If 40% of a ride's capacity is pushed to a later time, the line looks shorter, so guests who might have by-passed the attraction will get in line, increasing the wait time. Or, more commonly, guests grab a FP and get in line for another attraction, increasing that attraction's wait time than what it would normally have been. So when people are returning past the return window, it has the potential to seriously affect the standby line.
Personally, I think that too many attractions are using FP, which is what is causing some of the current problems. This results in people "waiting" in two lines at once (i.e., FP holders standing in line for attractions they aren't holding a FP for). In some cases, I'm convinced that the FP line increases the wait of attractions that guests most likely would have bypassed, so there is no real re-distribution occuring in those cases (like Peter Pan...though it would still be popular, most guests would walk by if they saw the wait was over an hour and there was no FP to exlplain that long of a wait).
Cast members make exceptions to the rules in order to accomodate you. They DO NOT have to accept a FastPass ticket after the allotted time, but most of them will in order to provide good guest service.
Is that true? Based on other comments in this thread, CMs do have to accept the FPs after the allotted time (on the same day, of course). I assume the times that they don't accept them they've been instructed by management not to accept them.