1. You know how we are. If it was made lighter we would still have a tendency to over-load it.
2. The GL1800 engine design is as good as it gets and has plenty power with the current technology. The leg and foot room only need some more refining.
3. Too many gadgets now.
4. Can't reduce the parts count if we continue to want more toys.
5. Everyone may not want air-wings.
6. It would be extremely difficult to make a seat that everyone would like. A lot of folks may not want to spent the high $$$$ on an aftermarket seat.
Having said all of that, I am on my 8th Gold Wing and my 7th new one and have been fairly pleased with the improvement through the years that Honda has made. Of course I'm the sort of guy that likes thing simple.