I tend to agree and disagree with OP, being an "old timer" who stayed up 'til 5am playing BG1 as a kid.
First off - BG3 is a sequel, even though it will start from scratch. It kinda sets the premises for "a little more right at the start". An introduction that sets the premises for future action is nice and attracts people. Just imagine the first Episode of Game of Thrones and the White Walkers in the woods - we didn't see them again for a loooong time. BG2 started with the most OP wizard we've ever encountered kicking ass and showing us how powerless we are. The story takes off right after the official D&D campaign "Descent into Avernus", and that's where all your tieflings are coming from. For sure D&D has changes since 2E with a much wider mix of races.
Regarding magical items, in BG1 you find a Ring of Wizardry right outside one of the first friendly places, as lvl 1. You find an Ankheg armor before nashkel mines. You have a +2 hammer with lightning damage and a long sword +1 with frost damage. Not to mention you meet an elf with a moonblade, a super rare magical artifact. An all this before you have hit lvl 3. You can even run around with a 2-handed +3 cursed berserker sword. And don't forget the belt of gender swapping And BG2 basically drowned you in magical items to the point that even my Bag of Holding was full. So far in BG3, we have a bunch of magical items with the odd "on use" effect that doesn't throw off balance but gives flavor. I would like to see far less items using surfaces however. This is just not a thing in D&D. And booming arrows throwing people off ledges etc. is just silly at these levels.
Regarding our origin characters, the only one with a truly over the top story is Gale, but he is also a very grounded character in every other aspect. The main reason they are all very "much" is simply because they can be played as an Origin character, and this is Larians thing. Bumping into Gith when you deal with mind flayers is kinda a thing. Same thing happened in BG2.
So to summarize, even if the intro is Michael Bay-like and you realize you've been thrown into something big, the overall setting in Act 1 isn't over the top and I do believe things will feel more in place once level cap is increased outside of EA (or if we're lucky, still in EA).
