I don't think I've ever seen beige subaru mats. In my opinion the black looks better, but also they stay cleaner. The beige mats would still show dirt and rub marks. With black you just hose it off and you are good to go.
subaru made their oem all weather mats in black only.... they made their carpeted mats to match the color of their carpet... aftermarket all weather mats (weather tech, rhino,...etc etc..) can be bought in a tan color... if you live the 5 boro of nyc i am willing to give you my tan carpeted one...(it's just taken up space in my house)