Like Isaid above, there were several things that went into the decision. First off they needed to go to a frequency range that didn't require licensing to operate in. The 3 easiest areas that would fit that bill would be 900 Mhz, 2.4 Ghz, and 5.8 Ghz. Next would be to look at the equipment already operating in that frequency range. Right now in the 2.4 Ghz range there are a lot of existing computer equipment already operating on 2.4 Spread Sprectrum.But here all of this equipment is designed to not interfere with each other. In areas such as 5.8 Ghz there is a lot of equipment already operating, but those don't get along with each other and could interfere with each other. Next would the the antenna size. Basically, the higher the frequency the shorter the antenna would be. If they dropped to a frequency lower than 72 Mhz they would have an antenna longer than the 39"used by 72 Mhz.

There are just some of the reasons why 2.4 Ghz was choosen, there were probably many many more.

Ken