Why write dissents? Or law review articles, for that matter?
Sometimes simply to vent. Or for credit. Or tenure.
But sometimes, they matter. Or at least get cited and seem to matter.
Here's an example of the latter. In a very good opinion by Justice Kline.
The Court of Appeal holds that it's a violation of the Fourth Amendment to take mandatory DNA samples from mere arrestees; e.g., individuals for whom there's been no determination of guilt (or even probable cause). An opinion that definitely matters.
It's worth a read.