mechmouse: I've emailed him several times. This is a reply from the developer
Crap, sorry about that. GOG isn't worth supporting for us because it's significantly more work for basically zero revenue. Sorry!
mechmouse: I hope people leave it at that and don't start spamming the developer that they should reconsider and publish it in GOG anyway.
The worst thing that could happen was that they would yield and reluctantly release the game on GOG... only to abandon it right away (due to their lack of interest), not keeping the GOG version up to date.
Too bad the developer isn't enthusiastic of releasing the game on GOG, but not every game needs to be on GOG, no matter the costs. I rather see GOG releases where either the publisher is excited to release it on GOG, or the game is so stable and complete already that it doesn't really need much of further support from the publisher.
Who knows, maybe months or a year from now when the game is more stable and not under heavy development anymore, the publisher reconsiders and decides to release it also on GOG. Fine by me, I'll look into it then; at least it doesn't appear to be yet another 2D platformer with pixellated retro-graphics (right?).
Anyway, today I bought Way of the Samurai 3 from GOG (already had WotS4 here). Nice to see releases like this on GOG, I thanked the publisher with my 10€.