T20 status teams..

[spartie]

But USA are big baseball fans, thats a long game and NFL goes for about 4 or so hours too.

All sports on North American television last about 3 hours, and with the exceptions of basketball and baseball, have a clock allowing 60 minutes of playing time....the only time an NFL game lasts 4 hours is the Super Bowl, and that is because of endless TV time outs and a halftime show that takes an eternity.
Baseball is not a long game. I have been to MLB games that have lasted just over two hours. Untelevised lower-tier games take somewhere between 90 min - 2 hours to complete, whereas an ODI takes over 3 hours to complete an innings, and the only way the game can go fast is if the batting team is having an abysmal day. T20 fits into that 3 hour box, and is therefore more accessible to a TV audience in the new world.