Can it be changed to look visually different from a PP or APP? This gets hidden among the mass of PPs. I agree that the previous way of doing things (putting a [NOTE] or [CONSTRUCTION] in a UR) is hidden also, but there are scripts that can show that visually.
There is guidance from wiki indicating that a map comment should always be added if one uses a TOI (Turn Instruction Override). But really, I believe that using a TOI for a left Exit or obvious situation is over using the map comments. The number of map comments would exceed the number of URs with [NOTE]
We just got a "bad" Map Comment similar to some of the "bad" PURs. This was created by a L1 with less than 100 edits. This most likely means that anyone, even those with 0 edits, can create one.
Again, we have to figure out the right amount of control vs openness, or the map will be littered with useless MCs and the concept will no longer be useful.