Give each dungeon a unique theme and goal.
In previous games, each dungeon had its own unique look and feel. The Divine Beasts were cool, but they all had the same general aesthetic. Each one also had you doing the exact same routine (find all the terminals, activate main terminal, fight boss).
I was very disappointed in the soundtrack. Some tracks were good, but the rest were pretty forgettable in my opinion. Every Zelda game prior to BotW had epic orchestral music that deserved places in Top 10's and whatnot.
A story that takes place in the present.
BotW's story wasn't bad, but it left a lot to be desired (especially the ending). Having nearly all the story written in flashbacks was cool at first, but then I started to realize there wasn't much going on during my adventure in the present day. A lack of story also means a lack of memorable characters with enough screen time.
Fill those empty fields of grass!
BotW's world isn't empty, but there's still too many vast expanses of nothing. Large empty fields of grass scatter Hyrule, and I can't help but get bored when riding my horse through them trying to get from Point A to Point B.