From carefully reading the CA fish and wildlife site, and other field herping forums who believe in following the law...I'm sorry, but I believe you're wrong. There are many species (and probably the venomous are included in that, but I can't seem to pin down the master list right now) that are restricted from being collected, but as long as you have a valid CA fishing license, you can legally collect and keep a certain number of reptiles and amphibians.
Yes, with a permit. That was my point. I may not have worded it well.
Why keep a snake? Why keep any animal? Because you enjoy the animal, find something beautiful and fascinating about it, and it fits seamlessly into your lifestyle.