Doesn't "Waste not, want not" mean that it's wise not to waste in the sense that, by not wasting what you have in the now, in the future you won't want for anything? I think there's a temporal factor to the saying. Also, I think the sense of the word "want" means "lack" more than our more contemporary (and limited) sense of word "want," meaning "desire." In other words, "Waste not, lack not." Does that make sense?
But here's one that flat-out pisses me off: "A stitch in time saves nine" Huh?