A 1400 would allow for lower revs with equal power. Lower revs= longer engine life, something that fits the sport tour style.(remember the miles on my ST!)
These bikes are not light, so more roll on power is a plus. 2 up riding with the bags and topcase loaded up require a bunch of torque for that twist the grip and pass without downshifting type riding. In this situation there is no replacement for displacement.
I read where that drawing is reportedly a Kawi design shop drawing. If that is true, they are on the right track to get my $$ :clap