I agree that the writing behind the companions is sub par at best and many people have brought up the incredible amount of plot armor and suspension of disbelief that is required for any of them to get their foot in the door. I have seen people also make the claim that older BG games where whacky humorous because humorous things can happen and this makes no sense to me. I'm sure you've seen a picture of soldiers laughing or playing a game during an extremely graphic war(such as WW1/WW2) but you would never propose that these times where humorous or whacky. Please consider the actual tone of BG1/2 and respect that despite this the developers had the clarity to still allow space for humor and entertainment.
That being said all the problems with the companions stems from the "origin character" gimmick that has made a return from DivOS2 and I personally believe was an extremely thoughtless decision on Larians part. Of course all the characters will feel like Mary sue snowflakes while also feeling underdeveloped because they need to be main characters while also allowing for you to take control of them and affect their personality according to your desires. This is ineffective at best and schizophrenic at worst and something I believe they genuinely need to rethink while there is time. If they don't then for me the immediate choice will be to mod these characters out of the game.
Lv 1 doesn't necessarily mean "clueless nobody who just started adventuring".
DnD allows you to create a character with an already rich backstory, full of a prior life, and that doesn't have to translate into "high level".
For the purpose of "ludonarrative cohesion", it is easily reconciled: Your character simply decides to employ abilities of increasing power just as the threats increase that require them (and as their "XP", as a representation of that, increases as well).
Level 1 means you are extremely week, completely inexperienced and barely skilled. DnD allows you to create a rich backstory yes but why do you ignore the fact that there is control for this and a GM will veto backstories that break cohesion by allowing you to write in a power fantasy? The last part is comical and is the definition of ludonarrative dissonance as well as being poor reasoning and unrealistic even in a high fantasy setting.
