I have been reading through different systems and find some angle the bottom half of the fronts back towards the side like this photo from the American Garment cutter when drafting the pattern. There is no mention about doing this for a reason this and has me curious if it is a style difference between countries or fashion types indifferent generations?
This example is a style. I would say it's very early, closer to the evolution from bodycoats than our current lounge coat.
With all that hip flare, it could be a riding jacket or a Western gun slinger.
A coat like this is probably meant to sit open. Where as my own coats are cut to close. I use a lot less angle on my own coats.