I think you're being very unfair on Marty! He's far from irrelevant. It's like you're punishing him for not producing works of genius on demand.
But for me, he's become the Elvis Costello of film. His best work was decades ago, but he keeps popping up in everything, spouting "his view" on the subject, like his viewpoint is needed to derive credibility.
But he's earned that. Like Peter Bogdanivich, he is a very well respected film historian, so his opinion is trusted and sought. For all it's faults, Hugo is a fine tribute to the silent era that benefits from his knowledge.
How often have we mentioned Peeping Tom? It was Scorcese who rescued that film and Powell's reputation.