Logical Chaos Theory

I found myself asking the same question over and over lately as I get in to doing more full flash sites. Why is it that there has to be so many differences in the way that Flex and Flash operate and operate together at that. At the moment I will always choose Flex before flash for building full flash sites because of the ease of use it provides when it comes to fluid layouts and other such handy containers and controls. If things like the Box class which is a super class to the HBox and VBox classes were available for use in Flash CS3 then the layout of Flash sites would not be near as difficult.