Oda backs away from the 1v1 fights because the crew got big enough that when they ALL get a fight, its slows the series to a crawl for a solid year.
But those 1 vs. 1 fights are not completely cut, they're just performed by non-Straw Hats now.
Robin being cheated out of 3 possible encounters in Dressrosa alone (Trebol, Gladius, Diamante) is the best example. And here we're talking about a crewmember who desperately needed some premium spotlight, so she isn't just regarded as a glorified Professor Layton with tits.
I mean don't get me wrong, I wouldn't want fights for the sake of fights either, that's not One Piece. And I don't expect Oda to come up with something cool and fitting for each member arc after arc. But when there's a great opportunity then damn, please deliver.