There absolutely are well designed barndomininiums out there, and if you do an image search of barndominiums, these examples are front and center. However, if you go drive around and see what is being built, they generally don't look like these examples.
I am not really thinking about finishes and features like stone and turrets, but more the fundamental principles of good design - things like proportion, balance, human scale, harmony with the surroundings etc. They tend to be big boxes with awkwardly pitched rooflines, a porch grafted on one corner, windows randomly sprinkled around and the front elevation dominated by enormous garage doors. I am guessing many are designed by a draftsman at a steel building fabricator who mostly designs industrial buildings.
I totally understand function over form, beauty being in the eye of the beholder, and that we should build what we like, and what brings joy. But I do wonder in a few years when these are no longer so trendy, what people will look back and think?
Anyway, each unto their own.