There is always a trade off to an advantage and speed is no different. There are situations where speed is a very relevent and desired commodity but it can also be a hindrance under certain shot circumstances. I could be way off base here, but I think the site is the reason why speed is becoming more and more necessary. It does make pin point accuracy at known distances more possible, but it also makes shooting at unknown distances difficult because the site overrides the minds natural ability to calculate everything for us and this is why the bows are getting faster and faster. They are trying to compensate for the yardage miscalculations of the archer.