There is more to the kit than just an allen wrench. It includes a stand for holding the watch during a change and replacement parts. Of course it has the wrenches also. What is good about all of this is that it makes changing the strap painless and risk free. I always get jumpy when trying to change straps for fear of munging up the lugs of the watch. It's great to have a "fear free" method.
It was a bit of a showboat thing, but Marc Hayek demonstrated using the kit underwater during a dive on the Anniversary model. That's how easy the kit makes it.
Jeff