I wonder if any commercial publisher today would even consider issuing a series with covers governed by such restrained design rules as the Penguins observed in the middle of the 20th century under Tschichold's influence. David R. Godine, the Boston publisher, at one time did send many of his books out into the world looking approximately as decorous as these, but in more recent years he has opted for the same busy & shiny pictorial look as everybody else.
Images here.