Damun I agree with you that there isn't anywhere it is written that scene selection is available in 8mp manual mode only not even in there user guide. Believe me this is how it is suppose to work in all xperia devices.They have restricted these options to work with max resolution/MP. But i am glad that these restriction is being lifted in latest Z5 series. So one can select higher Mp in SuperiorAuto too.
Just in case if you are interested check this.
