I think if they went 3rd person, I gather they would feel they would have nothing unique compared to Tomb Raider and Uncharted. Plus, it's inevitable that as much as people might want it, those same people are going to rip the game apart compared to those games. They would really have to over deliver to overcome people's expectations. I think there are 2-3 first person Indy games from way back when and none of them were well received from what I remember.
Indy's most famous game is a point and click. Kind of hints that Indy is more of an explorer than an action hero and the viewer is lured in and fascinated by all the mysticism going on in Indy's adventure. Although the character doesn't seem to believe in the supernatural himself oddly, even though he witnesses it firsthand.
Strange that he says that in Raiders although Temple is the prequel. At least chronologicaly.