I like to play as Barbarian, which has nothing to do that it is a veryyy powerful class, of course, it just allows me to run around with a loincloth only, to have maximum skin shown (to attract Shadowheart f.e. ...).

I don't understand however the role and place of the "Barbarian" in the Faerun world/DnD universe, as I'm not a DnD player. It is a strange class because it mixes combat style with social/economical/mayby ethnic aspects. A Fighter/Warlock/Cleric/Wizard etc. can come from anywhere, depending on personal abilities. Even a Druid can be a person who grew up in a civilized city and later went into the woods for tree hugging.
But a Barbarian? In the dialogs (where the Barbarian options are most often very stupid) there is an option to tell Astarion that I'm from Baldurs Gate, a big and civilized city. Then after being raised in a luxurous palace I went to the primitive combat form as Barbarian? Just because I can rage? And what about the Wildheart, at least that seems impossible for such a city background.

When I hear Barbarian, I envisage a warrior with a bit a "primitive" background, which does not mean that the warriors are necessarily strong, stupid and roar all the time. They are unarmored due to economical and pride-based reasons and utilize their inner wildness or connections to totems to prevail in the fight while preferring simple throwing weapons or bows for ranged. They despise magic and would not even use scrolls. They certainly would never wear pants (ok, that's very personal taste, I admit grin )So, the DnD Barbarian is only partly satisfying for me. He/she can wear medium and light armor, seemingly can be from a very civilized big city background (although wearing a rather primitive looking garment which is great visually on the torso but terribly unpractical and mage-like around the legs, it's sad) and can use ranged hightech weapons like crossbows and also magical amulets and armor in abundance.

It is as it is and that's not my main concern. But lore-wise, from where do the Barbarians come in Faerun? How do they behave? Is it even possible from a logical standpoint to be a Barbarian as main where you have to make some delicate conversations and act as an intelligent and experienced person for the better of the story? A person from a primitive background while being a wild rage based warrior, can be an intelligent, charismatic and experienced person, although maybe restricted by some educational deficits. The Barbarian in BG3, judged from the dialog options, however is not, he/she is a stupid strong hulk. I find that irritating.