I don't know what the heck I am talking about but just thinking...
Jeans came about when Levi (person) started producing them for the working class. It was rough, durable, and again...was for the working class. It has since grown into something else but to mix a sports coat (historically worn by wealthy) with jeans (historically worn by the working class) seems really odd with this historical backdrop. Call me a nutcase for thinking this but it's just a thought that came to my head. I guess I am not busy enough at work.Warning: Spoiler! (Click to show)
That is very true from a historical perspective. The nature of this world, however, is ever changing, and so is the nature of jeans. Jeans have become the go-to casual trouser for everyone, blue and white collar alike. So, combining a jacket with jeans is not necessarily seen as 'wrong' anymore.
I suspect most people see difficulty in combining jeans and a tie not from the historical perspective, but more from a formality perspective. Jeans are still considered to be on the very casual end of the spectrum, while a tie is considered to be on the formal side of the spectrum. These formality perceptions are of course caused by their history, but I doubt many people still see jeans as a garment solely for the 'working class'.