anomaly: 5 - Why aren't the most voted for games getting on there! WAH! UFO Aftermath got 122 votes (and still remains on the wishlist!) and got naff reviews too, when System Shock 2 is siting at 8650 votes and is beloved by all (except for me, I will admit, but I am special!)
It's all down to legal stuff. GOG can't just put games on sale without proper permission and contracts with the owners of the IP. Consider also that the IP to many old games changes hands several times. The original IP holders may no longer exist, for example, and it may be difficult to track down who currently holds the IP. Then, even once found, there is always the chance that the current IP holder does not wish to sell the game anymore.
So a game could very well be the most wanted game on GOG, but if the IP holders don't want it sold, it'll never be sold on GOG. The wishlist is merely a list for submitting your wishes. It is not definitive shopping list -- thus the inclusion of a game on the wishlist does not necessarily mean it will ever be sold here.
I know that's probably not want you wanted to hear, but that's the way it unfortunately is.