To a significant extent it seems to me to be a question of moral philosophy. But there are also practical objections—for example, I might have missed it, but I don't see "regularly smoke opium" as one of the listed recommendations. As far as increasing happiness goes I hear it's hard to beat heroin. Nonetheless most people who strive for happiness don't go the heroin/painkiller route. I think this says something about the desirability of experienced happiness by itself.