Op amp bandwidth analysis questions
For the OPA344 I read a GBW = 1MHz typ. 2.7~5.5=Vs

I agree  BW/Av= 1MHz/66.67 = 15kHz

The problem with uA rail to rail OA's is often driving a capacitive load ( as do most emitter followers). What happens is the phase margin reduces and a bit of overshoot may occur. So adding a pole at the GBW cuttoff helps improve the feedback and reduce the effects of a small capacitive load.  I have not personally verified this on OPA344 but know this helps some uA OA's for stability and overshoot.