I am literally squicked!! The thought of JJ and Reid as anything more than sister/brother is just wrong. JJ is married. Spencer is her children's Godfather. Will is Spencer's friend. It's creepy. It's weak writing. It's a cheep shot.
You want a powerful moment bring back Hotchner. That will stun the audience.
I love that Rossi is getting a happily ever after. (I hope)