Where it goes into touch can be vital - especially if it is a question of touch or touch-in-goal.
I'm sure nobody would dispute that but the risk assessment would tell me that, while the
consequence of a wrong decision is high, the
liklihood is low because of the presence of the corner post as a visual indicator. So
risk would be no worse than moderate.
On the other hand, ChrisR is suggesting that the
liklihood of a wrong touch call where a referee (often without AR/TJ) has to observe plane of touch, whether catcher is in the air, whether catcher has foot in touch or not, whether he catches or bats ball, etc is significantly higher.