Board game design/mechanic question: Why "hide" non-secret information?
This has been a question about board game design/mechanic that has been bugging me. From a game design perspective, why do some games make the player hide information from other players that is not unknown?
For example, in Catan, each player's resource hand is hidden. In Tigris and Euphrates, each player's color cubes are hidden. In many games, such as Peurto Rico and Small World, each player's victory points are hidden. The problem is that this information is not unknown to the other players. The exact amount of resources, victory points, etc that each players have is known with 100% certainty. The purpose of "hiding" this information seems to rely on the other players forgeting. However, in order to play such games optimally, it is advantageous to keep track of this "hidden" information. Thus, it seems to add an additional layer of skill to these games in the form of memorization which does not seem to be relevant to the context of these games.
Furthermore, you have games such as Dominant Species, Carcassone, Caylus, Ticket to Ride, etc in which the victory points are actually tracked on the board for all players to see. I do not see any explanation from a design perspective for why these games track such information and why the previously mentioned games decide to hide it from the players.
Is there a reason for this game mechanic in certain games or is it an arbitrary decision? Does this mechanic make it a better game or is it an unnecessary and irrelevant layer of "depth" to these games?