Actually, on further inspection, I believe my method does take into account your point about decision making.
Say we are fighting an enemy with 15 AC, and have not flourished. Looking at the table, with 0 flourishes we have a 30% chance to hit.
We would then need to make the decision whether to flourish at least one more time or not.
If we look down the column to 1 flourish, we see our chance goes up to 31.5%. This is because we successfully flourish 90% of the time on the first flourish, and then after that with a +1 bonus we will hit 35% of the time (90% * 35% = 31.5%). Making the decision to flourish actually increases our chance of hitting by 1.5%, even taking into account we may nut ourselves.
So the table can be used to determine if the decision of flourishing is sensible, i.e. this table does consider your point.