This is another silly argument, the UCI doesn't regulate bicycles sold in the shops. I can (in theory because the bike will cost as much as a good second hand car) go to the boutique bike shop and get a bicycle with all sorts of fancy electronic shifters, carbon fibre frame that is under 6kg. Those bikes are lighter than the bikes in the tour de france.
The fact of the matter is that the current design is near optimal and other designs aren't as well understood, aren't as cheap to make (it is three triangles made out of tubes stuck together with a fork shape at the front) and normally have some horrendous downside.
The fact of the matter is that the current design is near optimal and other designs aren't as well understood, aren't as cheap to make (it is three triangles made out of tubes stuck together with a fork shape at the front) and normally have some horrendous downside.