The biggest problem I see with 220 roll film is that it can't be used with the much more common 120 backs. I have no idea what MF camera makers thought when they created this mess, small format cameras could use 12, 24 and 36 exposure film without any modification.

By now it's a chicken and egg problem: nobody would buy a 220 film back on the off chance that one gets the film of choice for it and without such a back nobody will buy 220 film. Contrary to was was written here, 220 backs are not offered that much cheaper than 120 backs, at least not on keh or ffordes.