Yes, DnD combat is heavily influenced by luck and forewarning. If you are surprised and have lame dice rolls, you are probably toast, even if you are a ninja ( with or without cheese ).
BG3 has a number of implementations in to reduce the impact of such randomness, more so than any other remotely D&D-based computer game in history, and more is likely to come with the implementation of feats such as Lucky - which probably will be brokenly OP in BG3 due to broken rest mechanics. I would argue Larian have gone much too far with the homebrew in this regard though, ie virtually guaranteed advantage, barrelmancy, all the implementations that easily trivialize most if not all encounters.
Ultimately though, BG3 is a computer game that allows you to savescum, it's groundhog day all day every day till you get it right. As such the need for a balancing encounters that accounts for bad-RNG, isn't nearly as required as in a tabletop game.
Yes, exactly. Almost all computer games allow you to replay, and most have exploits, whether intentional or not. The goal for most game development is to cater for the widest set of playstyles possible, to encourage the largest player base possible.
That's why game series often change mechanics over the years, usually to simplify and broaden the appeal. Of course, that can be annoying if you liked the existing mechanics, but game development is a business, not a charity, so their reasoning is not necessarily the same as any given player.
In terms of BG3, I think that Larian's opinion is that they want to give you lots of things to do, and leave it up to you to decide what you use. I'm perfectly OK with that, although I recognise that there are a small number of choices that are not optional ( such as height advantage ) which can only be fixed by making that an on/off toggle; so I hope Larian consider making such mechanics optional.
