Has anyone used [a wooden bench stern seat for a NAUSET, EASTPORT, or SAKONNET 16-footer]? I have searched but haven't really found any mention of [wooden bench stern seats for a NAUSET, EASTPORT, or SAKONNET 16-footer]. I see that most [NAUSET, EASTPORT, or SAKONNET 16-footers] do not have stern seats.
Why do most [NAUSET, SAKONNET, or EASTPORT 16-footer owners] opt not to go with stern seating?
NAUSET, EASTPORT or SAKONNET Stern Seats
Re: NAUSET, EASTPORT, or SAKONNET Stern Seats
A wooden stern bench seat was standard in the EASTPORT. You can see one in this old catalogue photograph:

The EASTPORT model costs $160 more than the base NAUSET. That up-charge gave the you a rear seat, a fire extinguisher, a compass, and seven cushions. The more expensive SAKONNET model was intended as a fishing boat, so it removed the stern seat to improve the cockpit room.
The most reasonable explanation why most present day owners of classic Boston Whaler 16-foot NAUSET and SAKONNET models to not have a stern seat is that those models never had a stern seat.
I don't know that there is any basis for your speculation that most present day owners of a classic Boston Whaler 16-foot EASTPORT have removed the stern seat. Perhaps this may have occurred in some cases, but I don't accept that it is always true. A more reasonable view is that the EASTPORT was the only model to have the stern seat, and perhaps you just have not seen any old EASTPORT models.

The EASTPORT model costs $160 more than the base NAUSET. That up-charge gave the you a rear seat, a fire extinguisher, a compass, and seven cushions. The more expensive SAKONNET model was intended as a fishing boat, so it removed the stern seat to improve the cockpit room.
The most reasonable explanation why most present day owners of classic Boston Whaler 16-foot NAUSET and SAKONNET models to not have a stern seat is that those models never had a stern seat.
I don't know that there is any basis for your speculation that most present day owners of a classic Boston Whaler 16-foot EASTPORT have removed the stern seat. Perhaps this may have occurred in some cases, but I don't accept that it is always true. A more reasonable view is that the EASTPORT was the only model to have the stern seat, and perhaps you just have not seen any old EASTPORT models.