During the Kojima Productions podcast #159, the staff members gave some more insight into the decision to not update the controls of MGS2 and MGS3 for the HD Collection, to something more akin to MGS4 or Peace Walker.
People have asked us: why don’t you upgrade the controls to something more modern? If we were to do that, it would change the game completely, and I think people don’t really realize that. We actually did do experiments with that early on in the project. (..) It didn’t work. You would basically have to rebalance the entire game, and it would be like creating a whole new game at that point.
The staff members explained that while MGS3 does have free camera control, adding control features like crouch walking and run and gun would make the game far too easy. For MGS2, adding these features would be even more problematic.
MGS2 was completely designed to be from the top view. If you were to suddenly put a third person camera in there, it’s very confining and very hard to control. We tried it and it does not work.
When we make the games, we basically only make what you see. It’s like a stage set. You see the walls around you, but beyond that, there’s nothing. It’s just this big black space. So if you suddenly give the player the ability to look anywhere at any time while moving around, they may see things that they are not supposed to see, and it will totally destroy the illusion of the game.
Since Kojima Productions’ goal was to bring the classics to current generation consoles, the decision was made to keep the controls as they were, instead of rebalancing and essentially changing the games.
Source: Kojima Productions Report