Anyway, yeah, since that's an OXC bug, it's up to Meridian to decide what to do with it.
There is no right or wrong answer here, so I'll just share my opinion.
The original game doesn't find the optimal path either.
Without any hard evidence, I'd guess that it was a deliberate design decision... to provide players with more natural paths instead of the cheaper ones (at all costs).
(Optimal path algorithms were already well known in the 1990's and they were not too memory- or cpu-intensive.)
It's kinda funny because the code in Bresenham is like.. if (... tuCost == lastTUCost ...), basically, to check if bresenham is optimal path, the function only checks if there were any changes in movement cost from one tile to the next, so if you're running on expensive terrain (tall grass / wheat fields) the whole time, it won't notice any changes. But if it detects changes in the cost, then Bresenham will say "I'm not optimal path, don't use me". I've attached a screenshot where you can see that a straight line exists, but because there's one cheaper tile in between, it detects this change in cost and then A* is used instead.
This was definitely a deliberate decision from OXC devs.
OXC changed (I am intentionally not using the word "improved") the pathfinding algorithm to produce more TU-optimal paths.
But in a decent number of cases, TU-optimal paths differ from natural paths, which irritates a lot of people (including myself), and so the compromise you described above was made to produce more natural paths again (although not as many as the original game).
One example for all: when you start your very first mission and tell your very first rookie to go down the Skyranger ramp:
1/ the original game will take the straight natural path (as everybody would expect I hope)
2/ openxcom will take a funny, unrealistic path involving a jump down from the ramp... that both looks bad and in reality should cost a lot more than just walking down the ramp
(Let me just repeat that... the very first command you issue as an xcom commander on a battlefield, is executed differently in openxcom than most of us would expect. I can only guess how much this bothered OXC devs and how painful the compromise must have been. I definitely don't envy them.)
I personally prefer natural paths, which give me more precision-control as Yankes said, without too much hassle.
And they look better too.
That's why if I could choose how to fix this issue, I'd revert back to the original algorithms from 1994 and not use openxcom algorithms.
But breaking compatibility with openxcom would cause me more trouble (from all the nitpickers around) than it's worth... so at the end, I will compromise too and not do anything.
