I agree with most of the ideas posited here. OotS is very good at juggling multiple storytelling goals in a single scene.

Ultimately, I think it's just really fun to do a dragon fight. It's iconic and exciting.

The Order has never fought and won a straight-up fight with a mature dragon. The YBD fight was a short struggle followed by a Disintegration curb-stomp; the ABD fight was an even more flashy curb-stomp. It'll be really fun to see the Order take down a dragon, on even footing, based purely on skill.

Assuming nothing goes horribly off the rails, of course