I have to disagree with you on this point, starting with the fact that, for me, is something completely irrelevant (in terms of "judge parameter" I mean) and second, because if you really wish to follow the Role word inside "RPG" then you shouldn't be able to even grab 2 bottles of something, neither you should be able to carry 10 steaks of beef and neither you should be able to grab ANY loot at all (no more than 1 armor, no more that 2 swords etc etc etc), because let's face it, a normal human being (even if is a witcher) can't carry things like that, he doesn't have enough arms or space to keep all those things on his shoulders.
About the fact of "cooking food", like before i personally couldn't care less...not because i found it irrelevant but because this game is not an old-style full RPG , but it was always stated as an Action-RPG, there's a bit of difference.
Developers could take a bit of freedom on such things (like the food not cooked etc etc).
I individually found the underwater controls quite fine (i'm a PC player, i don't know about you) so i've nothing to say about that.
This game is not Dark Souls, or BloodBorne, or Minecraft or any kind of "survival" RPG and it never meant to be something similar so you have to judge the game between the limits of his nature and not for what you wish this game could have been.
This is not intended to be a flame, or and offense of any sort.
I'm just expressing my personal opinion about it