I do so because it would get crowded in the front. I carry a lot of stuff in my pockets: keys, phone, notebook, pencil, and wallet. None of those would work well in my back pocket but the (relatively thin) wallet, and trying to stuff more than two per front pocket is uncomfortable.
Diverging further from the topic - it sounds like you need a bag (a man-purse if you will). There is quite a wide selection these days in many styles. Also it's quite practical.
(edit: apologies if you are female, but since you need a place to put stuff I assumed you were not)
