Re the new boarding process.
It will be fine on long haul services. However on many occasions the
Last few passengers to board are premium passengers who wait in the lounges to the very last minute.
On short haul services given the short turnaround times the Quickest way to get the passengers over the aircraft threshold is to strictly board by seat row number from back to front. The problem you have is not boarding passengers at the gate but getting the customers seated and hand baggage stowed.