Doc, you may very well be right that speed is the most important factor in the outfield, but you are likely overstating its signifigance. There are several reasons why the behavior of major league clubs isn't as strong of evidence as it appears.
First, players aren't primarily selected for their defense but for their offense, and teams often wildly overrate the value of speed in putting runs on the board. Any fast player who can get the bat on the ball is tagged as a potential leadoff guy, and teams will often give such a player lots opportunities because they so badly want the guy to succeed. Slower players don't get nearly as much leeway unless they can really mash. (Also, if teams overrate the importance of speed on offense they probably overrate its value on defense as well).
Second, the fact that most burners play center doesn't mean that teams are "desperate" to put super fast guys there, but rather it's because it's the only place that makes sense. When I'm deciding where to play people on a softball team, the first thing I think about is who plays shortstop. That is the most difficult position because it requires the most variety of skills (quickness, reflexes, coordination, arm strength, accuracy, instincts, etc.). Speed is flat out not enough there. Outfield is a much easier place to play because you dont have to worry about ground balls and rarely have to make tough, quick throws. Add in the fact that lefties aren't even allowed to play the infield and it becomes clear that a huge reason speed pools in the outfield is because speedy players often don't have the skills to play elsewhere, not simply because they are in such hot demand.
Angles are fine, but it's silly to talk about them as making up the difference between a 10.2 100m and an 11.2 100m ... especially when the 10.2 guy is also a polished ML outfielder.
A big reason why you put so much emphasis on speed is because you are underrating just how big a difference in instincts between players there is. In past discussions you have argued that there are very small differences in this regard amongst major leaguers and therefor an underwhelming runner can't make up much ground on guys who are way faster than him. That's what you mean by "polished". This can't be true.
Take a look at the speed scores again. While there are a bunch of elite track guys in center, there are also quite a few full timers there who aren't anything special, guys like Jim Edmonds, Vernon Wells, Aaron Rowand and Josh Hamilton (and Gutierrez). Even Torii Hunter isn't real fast. So if there is a really big spread in speed among center fielders, and speed is the most important factor, then there should be a larger spread in instincts/rout-running among CF's. That's because the less important a skill is, the larger the variation there will be in that skill in the selected population (if something didn't matter at all, the variation between players could be totally random). The only exception would be if the unimportant trait happened to correlate closely with something that was important, but I don't think that is the case here. So in order for there to be a small difference between outfielders in terms of instincts (or at least smaller than the difference in speed), then instincts would have to be extremely important, in fact, the most important trait.
Last point. It needs to be remembered how little time outfielders have to catch most difficult hits. They usually have just a few seconds to run to the landing spot, and so a delay of even one second can be huge. Also, we can't really appreciate how much time is wasted by poor instincts because the plays happen so quick and because we aren't looking at the fielder when the ball is hit. If we could actually see how much range was lost by poor reactions and routes, I think we would be surprised.