The sorts of voters likely to vote in initiatives generally tend to be skew towards those distrustful of government. A bicameral legislature by its very nature makes passing laws more difficult, which is exactly what those who distrust government should favor.
I don't think that's the reason. The primary reason is that that kind of proposal would almost certainly have to be a citizen-initiated amendment. Politicians aren't really keen on giving up their jobs. In other words, if there's a serious proposal to adopt a unicameral legislature, it almost assuredly would not be coming form said legislature. Voters may be distrustful of government, but they also want a government that functions. California has a functioning government now, with a Democratic Governor and supermajorities in the Legislature. If it goes back to the gridlock and dysfunction of before, I wouldn't rule out serious governmental reforms. Personally, I think California would be far better off with a 120-member unicameral legislature (combining the current 80-seat Assembly and 40-seat Senate, although elected in 120 districts).