Exactly, pretty much the only fault with the 175 design was no gangways and a different coupler to everything else they ended up working with. The magic of the new post privatisation railway with no standards. Elsewhere, couplers were changed to get around that. That 175s were incompatible with sprinters was madness.That isn't a problem with 158s as they have unit end gangways so you can just couple them together, but the 175's lack of gangways makes them less user-friendly as 4/5-car trains.
Sadly, we haven't learned. The same happens with every new build.