Because I really, really like this game.;P

Seriously though, I just came back from the Postal Steam page and noticed that those guys likely screwed us out of another major update. It's refreshing to have an indie company that not only adds stuff to their game years after the fact, but to also add these changes to the gog version. Besides, gog often advertises enhanced editions or free DLC on the front page. I think the in-game soundtrack and artbook alone justify some extra exposure. Granted, they usually only do that if the extra stuff comes together with a sale, but still...

O.K. you convinced me. GOG should do everything to help raising sales for every dev who isn't treating them (and therfore us) worse than steam.

And they did:
https://www.gog.com/news/among_the_sleep_updated_to_enhanced_edition

What feature was removed? I cannot find it in the description.

Yeah, they would not advertize this ;) But like it was said here it's not possible anymore from within the game to change subtitles and audio seperately. There is a workaround by editing the config file but in game it's not possible anymore. I already contacted Krillbite and asked them if there was a reason for this and if it could brought back. You really have to experience this game in norwegian with subtitles in your language - I highly recommend it.