Looking at how high the percentage is in Maharashtra, it's not hard to understand the appeal of Marathi nationalism.
From a political standpoint this isn't important, but I'm curious as to what percentage of the people listed here as Hindi-speakers actually speak Hindi as opposed to some other language. Bhojpuri, for instance, is not mutually intelligible with Hindi (in fact it is in the same language family as Bengali and not Hindi), but for political reasons the state has always considered it a dialect of Hindi.