I’m in my 58th year and yes I loved the 70s sash shirts, the other home tops from that era are in the main instantly forgettable design wise. From the cost cutting plain amber to the short lived final 70s Admiral are two low points from that era. Although I still have a soft spot for our first Admiral home. And, the white Admiral away was a design classic.
However you said: “in the 50 odd years I've been following MFC I'd guess about half of our kits have had no hoop/band at all.”
The historical kit evidence clearly doesn’t back that up, as the majority had a band or hoop.
The separate issue is... Should the Motherwell home shirt always have a proper claret hoop?
To me there is no debate on that, as our very first shirt in that style had an unbroken hoop. That top set the ground rules which remained intact until season 1969-70. It was only removed due to the hoop stitching repair issues that was mentioned on this forum. The same can be said for the colour. That 1920s shirt was bright amber and set the tone for all subsequent shirts. Sadly the 1970s let the amber slip to yellow, probably due in part to laziness within the club, and the kit providers not giving an arse about our true colour. Luckily we have people in charge now who care about our claret and amber history, and realise we don’t play in maroon and yellow.