You could have as well said "Shimano likes selling more gruppos", since they want all the parts on one bike like-branded and the same style(?). It looks like a slow but steady market for the "flat-bar" gruppos, and even Campy has been making that style shifter for a few years now.

I checked out your GoldRush 'bents, and if you think YOUR rear fender mounting looks hokey, then you haven't seen my rain bike.

I wondered how's the steering on those, what with the grips behind the steering axis.
Intuitive steering I suppose, in that tossing the grips to the inside of a turn would automatically induce countersteering, much like some motorcycles with older-style (not "sportbike") ergonomics. Should keep beginners out of trouble if they go into the twisty roads carrying too much speed.
Then again, the weight distribution of these 'bents is quite different in terms of how body weight is distributed, and the saddle's position acts to some degree as a sort of pivot-point. It's been 10 years since I tried them out at Interbike.