Originally Posted by JandK
Originally Posted by mrfuji3
A big thing about deflect missiles is that you should be able to throw the arrow at any target, not just the one who attacked you. Which is impossible with an automated reactions.

Sure, I agree. It would be nice. Until then, I just don't think it's the end of the world. I'm okay with the way it is now, and I'd be happy with something even better in the future.
Yeah. Unlike counterspell/shield/absorb elements, nothing integral is lost if Deflect Missiles was a toggle. The monk probably wouldn't want to their reaction for a better opportunity, but simply deflect the first missile that came their way. Similarly, I (as a monk) probably wouldn't try to save my reaction for a possible Deflect Missiles if I was given the chance to AoO. So a first-come-first-serve toggle is mostly fine.