The comments on Pinkbike and Vital are at least consistently (and passionately) negative.
Might be one where consumer pressure wins out after a couple of years. It'll help sell bikes to newbs in showrooms for the moment because the bikes look neat, but won't help when they have to pay to get them serviced (people buying bikes with through-headset routing are unlikely to be the type to work on their own bikes IMO), or when the brake hose starts rubbing through the steerer (or even worse, if the steerer rubs through the brake hose), or rubs through the frame (the headtube is a fairly important area of the frame, lol). And then of course it's another point of dirt and water ingress that means headset bearing replacements will be required more frequently, extra labour $$$ at the LBS for "through-headset tax" and pre-covering potential rework when shit rubs through down the track - because even though the cable were setup correctly at time-of-install they've slipped and are now sawing through stuff, and then you can't buy replacement of the obcsure proprietary headset parts, new frame required, etc... Might be education by financial suffering I'm thinking.