It's a point of view thing.
My counterargument would be, how many authors are not aware that their scripts are broken because they expected a 0 to 359 output but never checked?
Also, for the purposes of scripts that use setDir, which accepts -90 or 270, it won't make a difference.
Additionally, I think it's a mistake to use it in a script if you are aware that it returns values that were not intended by the author.
If you weren't aware that it returns values other than the ones it says to expect, then it will fix things rather than break it. As is the case with relativeDirTo.