If you act only on existing wants or compulsions, you have no means by which to assess if the wants themselves ought to be fulfilled. What your position entails is that if you want something you ought to pursue it and if you want something stronger than you want something else then, as a mere determination by the strength of wants, you should pursue the stronger want. You have no means by which to assess the legitimacy of any particular wants except by the feature of their strength. If you want something more than something else, you should pursue the stronger want.
What if a person only wants what is harmful to others? By what determination can you say to that person: “You ought not want that!” YOU can’t because your position, as a moral one, is that people should (or simply do) follow their wants. You have no mechanism (such as obligation) by which to deny wants, since wants, for you, take precedence as a simple matter of fact.
Furthermore, this says nothing about conflicting wants among different groups of people. Politically, you are left with a model that mandates that the wants of the majority are going to dominate the wants of all minorities for the same reason you think stronger wants simply will dictate what any person, as an individual, wants. Again, your view of what a person is is going to affect how you see politics (and morality as its ground) working.
Political “right” is going to collapse into a right of the majority to impose its wants on minorities. So appealing to emotion, rather than sound ethical principles will be the dominant strategy and what got Obama and virtually every politician in modern western democracies elected. The tail - or, rather, the lower organs - wags the dog.