The higher pleasures are superior, for example a man enjoying the opera is happier than a man watching a cartoon, although both cause pleasure, the experience of the opera is far more worthwhile and valuable. Therefore, when deciding which activities cause the greatest pleasure, and therefore the best action, the higher pleasures should be given a higher value. According to Utilitarianism, happiness should be maximised at all times because it is an end in itself. People work to earn money, they wash dishes to have something to eat from, but people seek happiness, to simply be happy. It is at the centre of human nature, and people need to seek it.
Nobody wants to live a life of unhappiness.
Looking at the bigger picture, it is the goal of society to maximise happiness for it's citizens by deciding on actions which would cause the greatest pleasure, and therefore utilitarianism is consequentialist. Inevitably, there have been heavy criticisms levied against this approach. Unlike utilitarians, Aristotle separated happiness and pleasure. Humans don't just seek superficial pleasure as Mill would suggest, they seek true happiness. There is a contrast between feeling happy, and being happy.