forbidden

Dear scholars of Islam, as-Salamu `alaykum! I would like to know why eating pork is prohibited in Islam, despite the fact that some people claim that pigs are very useful, especially when compared to the slow rate of energy conversion to flesh (7% only) whereas the rate of pig’s conversion to flesh is 20%? I just want to know the wisdom behind the prohibition of pork in Islam. Jazakum Allah Khayran!