I doubt most game companies are taking specific ideas from internet posts.
Giving detailed suggestions to game developers may accomplish the
complete opposite effect: they’ll try to move far away from your idea to avoid being accused of stealing it. Thus, specific suggestion in fact hurt your chances of seeing what you want get into the game.
Check out this recent post by Harada, the game director for Tekken (one of the highest selling fighting game franchises), where he says this explicitly:
In this post, he tells fans to stop giving them ideas. Other replies have chimed in; one said he emailed Ubisoft ideas and they responded to him saying they explicitly try to avoid user ideas for that very reason.
