To be fair, he actually does get some more characterization in his supports with the Avatar.
And the notion of a character being recruited by having them survive the previous chapter despite not turning to your side in the actual battle isn't exactly a new idea (Douglas from FE6, Nasir and Gareth in FE10, Dart in 7 if you did the sidequest spring to mind), even though it's not the case with Gangrel.
When Snake sees a "!" over someone's head, he runs and hides. When the Pokemon Trainer sees a "!", he beats them up and takes their money.