Iger decide customers didn't want 2D animation anymore when Pixar had more success than Disney. John Lasseter said 2D animation had become synonym with bad story telling (it wasn't the format but the lack of creative freedom within the procedurally forced system that was forced under Iger's reign).
Too much content isn't the problem. Spider-man across the spider-verse (Marvel movie made by Sony) does very well. It's animation AND Marvel but it's very, very good. If people didn't want to see more Marvel it would fail. It also helps that it doesn't have a bloated budget to make a profit.
Of course Iger will never say that their content is low in quality and he will throw everything and his mom under the bus to make his point, and he probably knows the real problem but he lacks the quality to repair the problem without buying an outside company as he did in the past.