I would assume 2a s would not get the points to win with the dominance she has. Look at the NHK.
Mao won NHK by 20 points. The difference between a triple Axel and a double Axel is 4.2 points. So if you attempt a triple Axel and double it, that's not necessarily a disaster by itself.
If you rotate the triple Axel but fall, you lose 4.0 points, so that's not necessarily so terrible either.
If you don't complete the rotations AND you fall, you lose the whole element (you receive only 0.2 points instead of 7.5)
But the worst thing that happens is that when you flub your 3A attempt, that effects the rest of your program, you make other mistakes, and it's hard to get back on track.
Mao has attempted the triple Axel in every long program this season, so you have to give her an A for effort.
Kimmie Meissner, on the other hand, omitted the triple Axel at Skate America, skated great and scored 118.96 in her LP.
At Eric Bompard, she attempted the 3A, fell, messed up some more, and ended up with only 105.47 points. So again, the 3A seems to be an all or nothing deal. Not just because of the points, but because of how it affects the rest of the program when you land it and when you don't.
Just my take.