Pregen PnP D&D characters also aren't the same as Larian Origin Characters. Imo D&D pregens are most useful for their mechanics - everything is on the page and ready to be used. This is especially useful for conventions, where if you allowed people to create their own characters, likely you'd either spend 30 min to an hour on character creation and/or people would come with redundant/overpowered/incorrectly-created characters. Also for new players - I'll emphasize an earlier point that only the intro Starter Sets come with premade adventurers, to help new players get into the game without feeling overwhelmed at all the options during character creation.
Whereas Larian Origin characters aren't made to speed up starting the game (they slightly do this, but it's not their purpose) or to make playing the game easier (they don't do this at all). The main point of Origin Characters is to experience that character's story. So even if you argue that premade characters are a staple of D&D, this doesn't necessarily translate to Origin characters. A more apt comparison would be if BG3 provided premade builds and recommended spells/feats to take at higher levels.
There's a long history in DnD of pregen characters with personalities. It's not just limited to starter kits.
Several came with wonderful artwork depicting the characters, along with their backgrounds written out.
I daresay some of the best experiences have come from playing those characters. One of the joys is that the characters tend to be more complete than the typical blank slate a lot of the players come to the table with.
It's like acting. A good actor isn't necessarily a good writer, and so the actor can often bring the pre-written character to life better than they can create a character from whole clothe.
