as for platonic friends, where no relationship with them had ever happened, i can't see a reason not to, unless that person is your polar opposite in living. there are friends i would live with, and friends i wouldn't live with. currently i'm living with my girlfriend who is also my best friend, and it works very well (but that's diffferent, i'll admit. also a pretty cheesy statement.)
as for ftf's or fwb's or fb's, i'd advise against it, personally. once they are in the home it's hard to separate your living space. if you are hooking up with someone, they might start to feel a right to invade your personal life, or not really think of you when they are out with other people. who wants to hear their roommate knocking boots while you are sitting in bed not getting any!
there is the whole jealousy thing as well to deal with. even people such as my girlfriend and me who are not jealous types get jealous over some things. it's a normal human reaction that can get toxic if it's not addressed right away. and if you are only sleeping with said person, often times this means that communication isn't the best at that point.