Way back in the1970s my parents had a new "smart" kitchen from UBM (remember them?).
The under-drawer pulls and those for the wall-hung upper cupboards were OK-ish, but the over-cupboard-door ones definitely not - mum (and everyone else) often breaking nails in an off-target reach. And yes, the protruding edge of the extrusion was hard to clean, the cupboard ones were a dust-and-goo trap, and they didn't do the hinges any favours either (as you usually ended-up pushing down on the door extremity).
The laminated chipboard faces (MDF not being a thing at the time) were slotted centrally along the relevant edge to take the extrusion, which I assume was either pressed or hammered on in the factory. That didn't cause problems. At a guess the face chipboard was either 5/8" or 3/4".
Scarily, I actually found the exact units (below), even down to the colour. I think our tiles were plain white though, and the worktops were rolled-edge Melamine (still ubiquitous today), and i think there might even have been masons' mitres at the corners:
Obviously I can't do a Valentine Dyall impression in a text message, but basically,
"DON'T GO THERE!!!"
E.
PS: The base unit cupboard on the left of the picture shows exactly what the doors did (early Euro hinges, too). Mum's were all like that after a couple of years. The hard and shiny edge of the extrusion really shows it up, as there's nowhere else for the brain to focus on (normally we notice the handles more than the rest of the door).
PPS: A bit more searching suggests the "design" was by W.H.Paul Ltd., Breaston, Derbyshire, in association with the Design Council. WHP were bought out by Glynwed Holdings in 1972 (who seem to have been largely unsuccessful asset-strippers, and dumped most of their "metal-bashing" acquisitions in the early 1980s). WHP were never heard of again, and Glynwed finally expired in the early 2000s (having cut destructive swathes through a sizeable chunk of smaller British manufacturing).
and neither of us has excessively long fingernails. 
