I mean... explosion predictions are pretty obvious because they have a half-square outline delineating the maximum in each axis direction, which is the more fundamental part of that display--it uses lines in addition to the interior highlight area and not just relying on color like the rest of the targeting interface.
It might be intended to be the more fundamental part of that display, but what i automatically check to see if an explosion will occur is the far more obvious highlighted area. I wouldn't be surprised if that was also the case for a good chunk of players.
At some point, i even saw those explosion range line indicators and thought "wait, were those always there?". I might be good at noticing things generally, but apparently i can tunnel vision when i'm not in "parsing the entire screen for information" mode.