I've been told by my Japanese friend that it is the Japanese version of "lol."
I don't know why. But I find it strange how you're having problems with finding TDM and DM games, especially at primetime hours, because I never have problem finding games during those times. In fact, during peak times, TDM games usually have 15 vs. 15, 20 vs. 20, and sometimes recently, 30 vs. 30.
I'm not trying to call you a liar, so I'm sorry if you felt I did. But it's just annoying hearing people complain about matchmaking (multiplayer in general) in R2. Sure, it's not as fleshed out and polished as in RFoM, but it definitely works fine. Maybe you should try to search more than once, instead of expecting to be put into a TDM or DM game immediately after you pressed the button to search. I think I have over 300 TDM games played by now, so it works fine for me most of time.