I hate this phrase, it's the battle cry of those who do whatever their wife says and laugh with their buddies about how whipped they are. Marriage is a balancing act. Of course you have to change and give in where appropriate but if you do everything she says she wants you will lower her opinion of you (as it should, since you're a coward).
-- Socrates
But way to read too far into a silly little phrase and call me a coward, Mr. Anonymous Internet Man.
Not in my experience.
As for your "happy wife = happy life" theory, I'd strongly suggest running very fast away from women who implement this theory. You don't want people in your life who will drag you down to their level.
if she responds the way you're implying - I'm sorry, something is probably wrong with her.
In that case, something is probably wrong with most women.
It is known that in general, women respond most to emotional stimulation and men respond to sex. When my wife asks me to do something, she's really asking me to show her that I love her. And when she gets that feeling, she's very receptive to the idea of sex. Win-win, as they say.
However, many people fake the "happy me = happy you" by making you unhappy. That is often within their power to do. Then they give you respite when you do what they want. If you don't know better, you might mistake this for happiness. From what I've seen, this is how "happy wife = happy life" (or in it's more honest form, "if momma aint happy, nobody ain't happy") is usually implemented.
When my wife asks me to do something, she's really asking me to show her that I love her. And when she gets that feeling, she's very receptive to the idea of sex. Win-win, as they say.
It might be a win-win for you, but many people dislike trading labor/money/etc for sex (even when the trade is implicit). Personally, I prefer sex which is freely given for the sole purpose of mutual pleasure.