As cable sez, more power from a smaller displacement engine . . . . . which allows less overall weight, smaller chassis, potentially better handling, less costly suspenders for the same amount of filthy lucre . . . .
Making engines larger has a lot to recommend it, but it does start a snowball affect . . . .
But it's not quite that easy and simple.
I turbo'd a KZ 650 in the 80's...
To do it right, the engine needs to beefed up. virtually everywhere.
The tranny needs to be made to handle the power. Ditto for the cooling, chassis, suspension and brakes.
I'm sure there have been improvements and probably break-throughs, but they can't defy physics.
My turbo-650 was an expensive lesson that it's cheaper and easier to buy a bigger bike.