I think it was a temporary stop-gap machine--so KA could have a stainless-tank dishwasher to sell until the KD-24 models came out. The porcelain-on-steel tank 23-series machines must have started looking long in the tooth to many customers, compared to the glittering Bosch, Asko, Miele, and other European machines which were becoming more popular in the 1990s.
Mind you, I'd take a porcelain tank machine any day. But I imagine many customers in, say, 1994, opened the door on a 23-series Superba, saw their grandmother's dishwasher staring back at them, and moved on.
T.