I tried some scripts with help by Dolf, the pivot point could change to 'INDIVIDUAL_ORIGINS'. But, surely it's changed, I couldn't resize each faces with
bpy.ops.transform.resize(value=(0.7, 0.7, 0.7), constraint_axis=(True, True, True), constraint_orientation='LOCAL', mirror=False, proportional='DISABLED', proportional_edit_falloff='SMOOTH', proportional_size=0.0762767, snap=False, snap_target='CLOSEST', snap_point=(0, 0, 0), snap_align=False, snap_normal=(0, 0, 0), texture_space=False, release_confirm=False)
Why??? Is it a bug or something?
I'll try next way, 'Select one face, extrude, and resize. Because, in selecting many faces, the resize operation seems with 'Bounding box center', so if single face is selected, the center of resize will be set to 'the face center', I think. How about this.