To be honest, I'm both a bit disappointed and a bit...intrigued by the development.
I did expect Dragon himself to be there and some epic declaration of war (which is all he sent them to do as well. Sabo is the idiot that decided to try and rescue Kuma in the middle of the Holy Land. He forgot. his name isn't "Monkey D Luffy"). Instead, Oda decided to go a different way with Sabo endangering the mission.
It's a development that I wasn't expecting which actually made things more interesting instead of a completely predictable set up. So kudos to Oda for executing an exciting twist. Still did Dragon a bit dirty though...