I have to point out that, just like when you start college, roommate matching can go either way. And a two week trip is a lot shorter than a college semester, if things don't go quite right.
While it's true that on our OAT trips we have seen a couple of roommate matches that were not happy ones, several times we've met people who have made very contented and successful alliances. They might just have one fun trip together, or they might meet a new traveling companion. One pair of women we met on our last trip had been matched several trips before, six, I think, and each year they choose a new trip to take together.
I suppose, like most gambles, the results of being matched could be a curse or a blessing. You could meet a difficult person, but you could also make a wonderful new friend. Each person knows himself or herself best, and can evaluate their own personal habits and their own desire to take a risk.