In the topic where I presented this new walling method (see here), this was also suggested as part of the solution, more precisely to perform this walling selection using similar inputs as for the gate rotation.
I had no input from the devs, except this message (posted in a thread where I described the solution), but the result is exactly the solution I suggested.
The only difference is that the choice between Solution 1 & 2 (see here for details) is automatically done by the game instead of the player.
It seems that this choice is performed so that the longest wall section is on the side of the wall starting tile.
Yes, I agree, what really matters is to be able to choose between the two partially-diagonal solutions.
I added the 2 old L-shape configurations because some people were still interested in keeping them.
Please consider to remove the 2 L shapes from suggestions to make your concept perfect. It makes little sense to drag a diagonal line with the intention to achieve 2 straight lines, mainly it undermines the general efficiency and introduces the likelyhood for unwanted outcomes. Which is what this feature is trying to avoid in the first place.