Well, here you go, the answer to all of our problems, the Happiness Hat:
So, all we need to do is to make the wearing of happiness hats compulsory and we will achieve our goal of "Making Everybody Happy"...
Compulsory happiness is not the goal, I don't think anybody would want to live in a world with happiness police. And I suspect that is one possible side effect of governments measuring happiness, with any kind of measurement there is the temptation to massage the figures, find an easy way to make the numbers better.
But then we don't have that problem with GDP of Inflation or Public Spending figures do we? Just because a system isn't perfect doesn't mean it's not useful and if the government really tried to make people happier than it might well actually achieve that goal. And that could only help to make everybody happier!