Good points. My fatbike has internal routing (except dropper) and also the external brackets, so I could chose either. i had once replaced my shifter cable and housing and it was a pain internally.
Since my frames are black and i have a huge frame bag anyway, I don't think the external cables destroy optics.

The only concern I would have is the limited choice of external dropper posts.

I wonder how much cost and weight is added for the internal routing and the required reinforcements.

Obviously all "nicer"bikes come with internal routing. But does it actually enhance the riding experience? Sure it looks nicer, but now it seems to be a solution in search of a problem.

That Canyon bike he shows has a horrible design and totally pointless holes to hide a few cm of cable.