Legendary Dragon Improvment:
The only purpose for the legendary dragons is to gain raw Amber and then unlock the next legendary dragon. It would be cool if every time you unlock a legendary dragon you get extra dragon spots, maybe something like the hangar but not as big. For e.g when unlock the green death you get an option like the hangar when you tap on the volcano, this makes sense because legendary dragons have followers.
Some people have too many dragons on Berk so they have know choice but to send them to the hangar. Seen in HTTYD 3, every section of Berk can have those giant bird houses. It would be even better if you could see them in the roost and they can collect resources. The roosts can be like an add-on to build, maybe max three every section of Berk, I think this would really help people who have too many dragons.