The geometric changes to the fuselage were limited to tail cone reshaping and some modification near the stabilizers that remove the need for the vortex generators on previous models while improving fuel burn through better aerodynamics. The engines (larger) were located on new pylons that, in addition to providing the necessary ground clearance, provide better aerodynamic positioning relative to the wing. The primary notable software changes relate to spoiler operation that reduces weight and improves flow and stopping distances on roll-out.

These drawbacks somehow add up to a 21k increase in MTOW and a range increase of 800nm at slightly higher cruise speed.

I'm genuinely curious as to the aerodynamic drawbacks you reference. As for statistics, they can be tailored to any point desired. We could look to the a320 and note a window in time at which 33% of the in-service fleet had crashed (AF296 at Habsheim). That was not an indicator of the airworthiness of the a320, and it is highly speculative to make similar deductions regarding the MAX at this time.