POGO pins wouldn’t really impact waterproofing unless I’m missing something (similar to how you can have a USBC / lightning port on a waterproof phone).

Is super the real reason is this would have limited value because:

A) you have this already through cable charging

B) it’s not clear it would meaningfully change the charging speed since you’d also need a communication standard (eg USB-PD) to negotiate the charge rate

C) all of this is made moot by the fact that most people have a case on and don’t take their phone out of their case to put it on a Qi charger which negates the benefit.

So basically cost and complexity for limited to no value. Of course maybe C is solvable by extending the pin through the case but I would think it would add cost to the case + maybe create some structural challenges negating the shock absorption.