Not only the extra weight, but the airworthiness must be recertified every time the pod is reattached. After all the mechanical, pneumatic, and electrical connections are made, they must be certified by someone (read criminally liable if there is a screw up), then inspected by a certified inspector (again liability creeps in).
Constant couple/decouple operations will result in wear and maintenance, taking the whole pod and/or flight frame out os service. Maintaining 100% interchangeability among all the pods and flight frames is not an inexpensive endeavorer.
Easier solution is more and bigger entry/exit doors to existing aircraft. Use more than one jetway and board from ground level as well.
Pre-seat people in the exact order the are going to board, every third row and stagger entry. That would make it quick and simple.
We’ll load rows 48, 45, 42, etc. first, boarding in that order.
5 minutes later, 47, 44, 41, etc.
5 minute later, 46, 43, 40, etc.
All done in 10 minutes, no standing in the aisle waiting for someone to load the overhead bin, so you can get past.