I think Thor Ragnarok has two purposes:
1) To remind the audience that, no, the two supposedly strongest avengers are not invincible and can be defeated by thanos anytime
2) To make the audience have a good time before IW comes out so that the inevitable deaths of most of the avengers could hit them twice as hard. This laughter that you’re hearing in the theatre? You won’t be hearing that next year. This is the calm before the storm, people