Hi !
I think I was actually the one person who said around 2012 "pleaaaaase keep the yellow triangle cursor alive".
The reason was that at the time, some bug made the vertices show differently than they really were in the viewpoint, while the cursor was showing the real height. It was creating spikes ingame, and the cursor helped smoothing and correcting them one by one.
The bug is long gone (it might have been Hanfer who corrected it), so this cursor shape isn't indeed really useful anymore, at least for me.