beautiful sounds, my friend! and yes, i agree that this would be nice. right now, i love the rain sounds, bird sounds and the occasional stark, lonesome wind sounds that the game gives us in the winter. but i would agree it would be better with more!
I assume part of the reason that the game includes minimal atmospheric sounds currently is because they would get repetitive after a while. indeed, even the rain sounds will noticeably repeat with enough play. However, as you pointed out - there already exist 10+ hour playlists of unique atmospheric sounds! so perhaps this wouldn't be as much of an issue as it initially seems. In the end, it's all up to how Sami wants to handle it.