Derpdad93: It could also be that GOG forgot about it :(. In my opinion, the 90's were the golden age of gaming when it came to new ideas and imagination so there were A LOT of games being released at that time. I even remember playing 1995's Rayman and Earthworm Jim 2 which were silly fun back in the days. Now everything is focused around shooters and realism / graphics and developers forgot how to use their imagination.
Is there any way to start a petition regarding old games we would like to see on GOG.com? If so, it might help to bring back these forgotten gems :).
You can use the Community Wishlist, there are two entries for A Bug's Life, each with about 40 votes:
You can try to get people to vote them so that GOG will prioritize it.