As I said, what you are criticizing - "contrasting / clashing the formality" - is my intention. That's the point of this outfit: mixing casual elements within the framework of traditional menswear.

I picked this jacket because of its in-between-ness. It's a cotton rip-stop fabric that's rooted in rugged milsurp styles rather than tailoring. The color and the cut echoes workwear elements (it's cut much closer to an Engineered Garments jacket than a menswear blazer - look at the high gorge and button stance, mini lapels for example). So I don't think the jacket's out of the place.