There's more strategy in the Ten10 matches than you think. If you pick a high number as your bonus ball, you lower the total score, if 6 is your bonus ball, the opposition can't hit a six, if you have the last over as your powerplay, you might get them all out before then, if you use it too early, they might lose some early wickets, but stay in the whole way through. If you choose a low number as your ball, that means when batting you can turn the low runs into higher scores - or you can go for a middling number and balance it all out.
Should probably have read this somewhere before deciding on the numbers...