AC DC is probably the most successful group with the simplest music of all time. I'm not saying Cliff Williams is an absolute disaster - he could keep time (as a bass player should). Every single song is in 4/4 using open E and A strings and some combination of 3 other notes, usually of which are G, C, and D. I mean could he be any more of a one-trick pony than that?
Much is made about Michael Anthony being an average bass player. I've seen it here in threads several times, with the knock that all he played was 4/4. Except Anthony IMO came up with more complex and interesting parts that I've ever heard from Cliff Williams.
The band wrote many good, catchy songs however simple they may been. And yes they did them well. I'm not disputing that Cliff Williams is not a legend, at least for the very fact that AC DC was so famous and have been around for more than 40 years.
To me AC/DC could sort of be considered the McDonald's of rock and roll, they sell the most burgers but they don't taste the best.