Hi,
I think that the game sold less mainly because:
the main story (less inspired) and the pirates setting that maybe seems strange related to the lore of poe.
Surely there is also some marketing /communication aspect involved and that were coming out other similar pc games.
As my personal opinion about the game I would say that:
I found the ship system and the "open world" exploration boring. I think that whit the poe1 map you can focus more on story and progression (related to main story problem).
combat system and mechanics I think that are good and multiclassing is interesting and funny. I don't like resting with food because is too easy and also the empowering mechanics for me is not adding anything. I also don't like that you really don't need healer classes.
In the end I would say that when I replayed the game I liked it more than the first time because I was focusing less on story and more on combat.
So in the end I completely loved poe1 instead poe2 was a really good game but that couldn't hit me as the first one but I still think that the game deserved more copies sold.
I still hope for a Poe3 with the best about the poe1 and 2 that could reach all the rtcwp fan base.
Sorry for my English cause I'm not a native speaker.