mmhh no, I think you have it backwards.
you are complaining because you are getting more options, makes no sense.
that's like complaining about an JRPG because it offers gamers the possibility of grinding to level 99, thus breaking the game and then saying "this game is a turd, I grinded to level 99 and battles are now boring, bad developer made an unbalanced game"
No it's not. The new mechanics don't end at just the first-person aiming system. You also now have the beefed up AI for guards. Guards can now notice you if you're just outside of their vision cones. This wasn't as much of a problem in MGS2 because the levels were designed with that feature in mind. MGS1 wasn't, and leads to a lot more problems because of it. There's less areas to hide in during room clearings, the more cramped areas make it much easier to get spotted. Because of this, the best option for sneaking across a room is always going to be "as soon as you enter room, stand in one spot and pick off every guard from first-person view". The bossfights weren't updated with this regard either, turning stuff like the Ocelot fight into a shooting gallery where you never have to move an inch once the cutscene ends.
Even if you deprive yourself of the most overpowered option in the game, you're not getting the same experience as MGS1. If they were going to add in MGS2's mechanics, they should have updated MGS1's level design to accommodate for it. As it stands now, from a mechanical standpoint (not even regarding voice acting, music, cutscene direction, the weird changes in dialogue, the lack of any bonuses, how fucking ugly it is), it's an inferior game. If you want a good remake that does it right, play Resident Evil on Gamecube.
Edit: I also have to point out that for the most part, out of all the updated mechanics brought over from MGS2, first-person aiming is the only one that sees any use. Rolling, ledge-hanging, leaning, bleeding, and hiding in lockers are all pretty much pointless, as there's never any ledges to hang from, they didn't add many lockers to hide in, and leaning/bleeding just makes the game easier when you can squat down and recover a bit of health while aiming from almost any direction. There's also the fact that you start the game with a full, huge healthbar and max ammo capacity from the get-go, instead of having you build your your lifebar and ammo capacity as the game progressed ala MGS1.