- The moaners who already have the game in Steam or whatever their choice of service is can simply skip buying it. No need to bitch about it every time, as if GOG owes it to you _not_ to release some games (what a stupid idea anyway).
- GOG is the only one who has real data whether it makes (or not) sense for them to release games that are sold elsewhere too. You guys are just guessing.
Either way, it is stupid to think that "everyone has the game already" just because it has been in some random time-limited "Be Mine Royal Indie Booyah!"-bundles. Not everyone is running after the random indie bundles all the time, especially the ones offering only Steam-keys.
You should get to know what sales potential is. I am almost sure Eschalon will not sell well on GOG. Just like many other previous releases that were just... too late. And you say that this is guesswork - well, bestsellers list is avaible to everyone, so you can at least compare how games that everybody has sell.
And this is a special case, because as we know, GOG refused to sell Eschalon games long time ago. They changed their minds. I say, it's too late.
Also, you really think that people who say "everybody has it" mean that literally?
I might be wrong though, because RPG fanbase is quite strong on GOG.