Just because you're very good at one thing doesn't mean you're good at another. Sometimes the further you go down one path, the less you know about everything else.
Hammond didn’t pick him, the insurance company did. The company insisted on only him, likely because he was a notorious skeptic who would be able to look past the sensationalism of the dinosaurs to let them know a realistic risk assessment. The dinner scene where he and Ellie criticize Hammond is exactly why they wanted him there.
Point being, no indication is actually given that he was smarter or more published than the others in his field, because that isn’t really what the insurance was after.
No it's the insurance company. It's that scene the very beginning where the lawyer is going to visit the the guy digging for Amber. He's the lawyer for the insurance company, he mentions that he's going to get Grant. Then the other archaeologist says he won't get Grant cuz Grant's a digger. Which now I think about it I guess means that Hammond is interfering with the impartiality of the evaluators by bribing them.
Gennaro: (Slightly dazed) If two experts... sign off on the island, the insurance guys will back off. I've already got Ian Malcolm, but they think he's too trendy. They want Alan Grant.