i'm not sure make the ninja go with the blm acc will affect anything, i'm curious to see what you really means by this. since ninja most skill are weaponskill and then recquire the same acc than dragoon and monk.

the trouble with the add of positional is not about the jobs is too easy and make it far stronger than other.... since positional have nothing to do with the dps. ninja positional is a trouble since the jobs wasn't designed with it inmind.
the combo system used by the ninja is not adapted. the mudra systeme is broken because of the lag, making it more complex than needed increasing more the difficulty of the jobs... adding positional will simply mess more the jobs. instead to make it more fun or more interesting it will make it more complicate for nothing. since positional is only a mere restriction, not a boost.

ninja have still the only systeme broken (mudra and it lag), a combo system quite basic (actually we are only using one combo branching with 3 finisher, spinning edge are the starting point of everything), the only positional unforgiving (TA still work like the previous positional system dragoon was using, making if you miss the positional, you don't get the effect of the skill)
and they plan to add positional on top of this? seriously... you did notice that a tons of ninja have already drop out of the jobs simply because of the mudra lag.... and believe me the add of the positional will not please player it will frustrate them more than anything.

i don't say is not possible to use positional, but that the skill level recquirement will be too high for most player.