I personally have no strongly developed opinions on splitting states up; I'm interested in arguments in either direction. But the idea of splitting up a state with (at least) two portions that are quite far apart geographically and culturally doesn't seem ridiculous on its face. But I'm also not sure where that argument ends. I'm from another state - Illinois - that spans quite a few latitudes and has at least two quite different cultural zones. When I lived there, it always seemed to me that you could quite reasonably split the state into three: Chicagoland, the agricultural midlands, and the south. So if it makes sense to split up California, does it make sense for Illinois too? Are there other states that the same argument applies to? I dunno, I'm curious about it. But of course it is a non-starter politically, so it's just an intellectual exercise.
Because splitting up into multiple states is not the same as seceding.
[1] http://www.sacbee.com/news/politics-government/capitol-alert...
[2] http://www.newsweek.com/trump-russia-jewish-farage-brexit-69...
See: http://www.bbc.com/news/blogs-trending-41853131
Edit: This is a direct explanation of why "just 'cause" is misleading or incomplete, based on public information from mainstream media.