That was almost certainly done to prevent drivers on the minor road approaches from traveling directly through the intersection. With the high speed limit on US-377, the curvature of that road, and the skewed approach on the minor road, it looks like that “right turn space” you describe was eliminated because it was considered too dangerous to allow drivers coming from a dead stop to drive safely across the two directions of travel on US-377.
Well they should have factored in the lesser of two evils, or completely realigned it to be directly across from the opposite street. Because human nature dictates they are going to cross both lanes to that opposite street anyhow, and this change here makes it even more dangerous because it is no longer a straighter path across those lanes. They almost have to double back and then make a whole additional left turn maneuver after making the right turn.
So what they tried to prevent/discourage made it even worse because they are going to cross both of those lanes anyhow, no way to prevent them from doing it without completely blocking access entering the opposite street. You always have to factor in the human nature aspect. Is discouraging it going to prevent it? No... So one must factor in this reality also when designing things like this.
Since you are a civil engineer please let me share a local reality with you explaining real world observations based on road authority neglect. We have a very old 30 mile section of the original two lane historic Route 66 here. The passing/no passing lines were engineered and painted back in the 30s when everyone drove 45 Mph as a norm because of the cars back then. Now everyone drives 65-70 along this remote road.
Most accidents on this section of road are head on collisions. Because I have been in the wrecker business in this area all my life I made an observation years ago how these are happening and what is causing them. The cause is the county refusing to reassess the double line passing no passing distances. They just keep repainting the original lines from when traffic only traveled at 45 Mph.
Those distances are now completely irrational and dangerous at the speeds currently traveled. There are dashed passing zones where there absolutely should not be any at current speeds. There are blind S-turns that have a passing zone in between the turns, when it should be a double yellow no passing zone all the way through the S-turn. At 45 you might have to time pass in this zone, but at 65 there is absolutely no way it can be done safely. When I was still in business these turns used to get me an average of one head on fatality a month.
Yet still they refuse to reassess the situation and repaint these lines with distances more fitting for current speeds traveled. Part of it is human nature, folks see a dashed passing zone they are going to pass whether they can see around that corner or not. So in this case it is the opposite, the road authority is neglecting to take human nature into account and discourage passing in these dangerous areas.
And their excuse? “It is historic so we can’t change it”. Yeah... Well... Things change and need to be reassessed if you don’t want to kill people with neglect and inaction of you are going to allow people to travel it at all.