yes, i think you are right, to express the same idea, we used to say "it was a war to end all wars" or "a party to end all parties" and this was even shortend to "the end" and a really good looking guy could be "the end" .

when hussain used (or was translated as saying) "the mother of all wars.." it resonated. it wasn't the same tired old cliche, "a war to end all wars" but it had the same flavor. and it was close enought to "a mother of a ______" that we all understood it.