I agree that this is a very disappointing series so far after all that hype, but did you really expect Hulk to have a good showing against Thanos, because I didn't. Someone who can smile off a full hammer blow from Thor and almost kill the Silver Surfer is not going to be intimidated by the Hulk.
- You have just described Rulk - he smiled after taking a killing double handed Mjolnir strike to the face from an Odin-powered Thor and outright killed the Silver Surfer before time was redone. In contrast Thanos was arguably more effected by the shot he took from Thor in Infinity.
- Thanos has himself stated (under Starlin) that he is wary of the Hulk because of his dynamic strength.