I don't think Dragonborn are stupid. I accept them as a fantasy element.
What I find unbearably stupid/annoying is the way all the races are forced together into the same culture. The serving boy at the inn could a dragonborn or an elf or a tiefling or a human. There's no difference. The races have become costumes, nothing more. It completely destroys the setting, imo.
I'd rather see the races presented as having their own societies and cultures. Where an elf is long lived and thus almost mystical and frightening to a human. Where caste systems are in place, where tensions run high, where alliances mean something.
As it stands, it currently feels like a random race generator was used to pick whatever race the NPC happens to be, regardless of the role or place in society.
