Yes, but that is just a truism. You might as well say good complexity is good and bad complexity is bad. You've just used fancy words to connotate 'good' and 'bad' in this context.Necessary Complexity is good, I suppose, Needless Complexity, bad.
The question you should be asking is, "How much complexity do I want, and why?"
Back to the World's Simplest RPG. It's a complete system. However, some problems with the system are immediately forth coming, such as that the propositions, "I jump over a puddle.", "I jump over the Atlantic Ocean.", and I get up from my chair are equally likely to succeed. The results that we achieve using this system might be funny in their incongruity, but unless that is what we are going for we are likely to become dissatisfied with this system over time, and the longer we play it the more dissatisfied we might become. So, while the World's Simplest RPG is complete and universal and as rules light as it comes, there are still things missing from it that make it a good game.