Why can men become aroused everyday?

I think a lot of these questions can be answered in the fact that distinguishes humans from much of the animal kingdom, we have become so able to adapt and survive in our environment that basic survival is no longer enough for us and we have therefore sought other pleasures from life; such as art, music, kite flying or even chocolate cake. We find some need for a greater meaning in our lives than that that comes simply from respiration or the consumption of essential proteins. Now, some people might take this search for pleasure and inventiveness to levels that are considered "too far" such as you mentioned about pornography that portrays much more than reproductive acts and while I do not necessarily support the grotesque oddities present on some of these sites, I would like to bring up that most of the people and things that we deem as "genius" have come out of perceiving differently and searching for more than can be found in basic survival. And now it sounds as if I've called raunchy porn genius which is not at all what I meant to say, I find it rather disgusting actually, but I merely meant to try to offer some explanation as to why it is created, and perhaps it has devolved into incoherent ramblings at this point, but I attempted an explanation and that's good enough for me.