We could just have a system like what Subnautica uses, where when you start the game you choose the level of difficulty and which survival elements you want in place. I do appreciate this adds strain to the developers to balance the game for all 'modes'.
I personally think the finite O2 is a good idea and here's why. How many times have you played a game like Oblivion or the Witcher 3 where the core challenge of the game disappears due to levelling up. The exploration then starts to feel pointless and dull. I'm not saying give players 3 minutes to get O2 plants working from the second they land, but make O2 something the player needs to consider.
Let's face it, right now the atmosphere and planet are the main characters of the game. Most developers would take the easy route to 'challenge' and add mobs. What if the planet was the challenge. I'm talking about dynamic volcanic activity, gas pockets that blow pieces of the surface into orbit (and if your friends can get to you in time save you), sunlight that heats the surface up (think Riddick) and so on. When you go in this direction your supply of O2 becomes the game's currency and the reminder you're not sat on earth watching your garden grow. You're in a hostile environment and having to O2 to consider would take away the key motivator for the player.