Originally Posted by urbanknight
As far as I know, they help to keep dirt out of the fork's internals. Not sure how well it contributes to this cause, though, because it sure isn't sealed nearly as tightly as the seals around the fork legs.
Fork boots would tend to blow up a bit, like a balloon, on the compression stroke, if they were sealed tightly. That said, there needs to be a small air hole in the boot to prevent this. Unfortunately, it will then tend to suck dust and dirt inside, essentially defeating its intended purpose. I beleive that is the basic reason most shocks now come without boots, coupled with the fact that the slider seals do a pretty good job of sealing out dirt. Lose the boots. But keep in mind that all forks will need periodic cleaning/servicing anyway.