Sam,
Lots of F18 sailors attend regattas like Texel with the intentions of winning, therefore the handicap system is very important. We don't need to worry about it a lot but it is something we have to keep up to date. I believe Eurocat and some other major regattas also have a distance race that's scored on handicap? Not to mention our little races over here.
I disagree with your perception that the class is tapped out with hull shape and current foils. Boats all have different chord lengths, shapes, and etc. If it was tapped out everyone would be using the same blade. In addition, manufacturers are still toying around with where the best placement of the board is. While the boat is most user friendly with it at the shroud, it's still not known if that is the fastest place to have your board. There's even been talk about having it in front of the beam but no ones figured out how to keep the load off the rudder in this situation. But if someone could who knows if it would be faster.
All the developments coming through these days are minor but that's what is keeping the class alive. I definitely wouldn't say the development is done anywhere, but it is hard to imagine any kind of game changer coming along which is exactly how we want it.