>I've always been amazed why the 2CV is seen as a styling icon

Round curves and lights looking like eyes, with proportions close to a human face.

The same design cues that made the VW Beetle and the Mazda Miata (1st gen) popular cars.

And "barebones" can be a quality. Citroen did tons of overcomplicated cars too, and for all the love I have towards the DS, the CX, the SM etc., they all suffered and keep suffering of reliability problems that killed them commercially and to keep them running nowadays.