One reason you don't see that many 11-87 barrels, or as many of any barrels for any gun of more recent manufacture, is choke tubes. Before choke tubes, many of us, who
HATE PolyChoke type devices, bought different barrels with different chokes for different uses. Along with the introduction of the 11-87, Remington also introduced RemChokes. Thereafter there has been much less demand for extra barrels in general. People may add a deer or shorter HD barrel, or add a long barrel on a deer gun, but they don't buy a RemChoked barrel and sell the old fixed barrel like so many have done with older 1100s. I have 11 barrels for 6 Remingtons, now, and at least one for each gun has choke tubes. I used to have a lot of barrels.