That's true of cars; but, I suspect, less so with motorcycles. The frame has to be much sturdier to handle the power and the weight of the power package. Suspension, front and rear, has to be more substantial to handle the additional weight (800 pounds on the ST, versus 280 for my now-departed XT250).
Wheels, sprockets (if equipped) and brakes have to be basically re-designed for different, harder use.
There is, of course, the tendency to just up the price with the displacement; but I think less so today More common is the shifting of the norm - and that's what got Honda in trouble with the ST. Go big or go home, the market seems to be saying. Honda went big, and wound up with a two-wheeled car - and not an especially sporty one, either.
I don't know where the weight is coming from, comparing 650-1000cc bikes of thirty years ago, to today. Is there that much emissions hardware that just the weight of it bumps up the Wet Weight a hundred pounds? The original Gold Wing was IIRC 480 pounds. A big bike for 1975. Now a simple mid-sized standard weighs more.