Not trying to sound superior (ah wtf ofcourse i'm trying to sound superior!) but i have a theory about why tb is dying.
It's all thoose damn braincell-killing games like WoW and LoL, CoD, and all other games with a small "o" in the middle of their names.
People don't want games that are hard to learn, they want mindless fps/moba-games.
In my opinion, prettyh much all moba games are either the same, or very similar variations of about 4 different original moba titels.
Almost all fps are the same... goes without saying really.
TB is innovative, dynamic, different. And you can do so much with so simple mechanics.
But still most people just say "DIZ IZ 2 HARD! GIMME THAT NEW COD GAIM; COD:MW:206849875900888786544! I'L KIL U NOOBZ!"
Also, i found that there is an unusual amount of left-handed people playing TB compared to other games.