Less worried about preconditioning the battery, more so the cabin. It might not be a frigid wasteland down here in the winter months but we still get frost, and the summer mornings can be rather thick. I want my car defrosted and warmed when I go to leave, or dried and cooled in the summer. I used to accomplish this in winter using a small heater fan, timer, and extension cord in the ICE vehicles.
I've done the math on previous usage patterns (I'm an engineer, this is what I do...) with full hourly pricing records. Summer non-charging expenses are pretty much break-even, and winter should save us a ton since we have a heat pump and heat strips for aux (which run hardest when it's coldest out).
We just got our first bill on the EV plan today and my numbers were almost spot-on. It's pretty much cost-neutral for us, just making a couple of minor habit changes (primarily, not running the dryer during peak times). It still wasn't the highest bill we've had in this house--winter used to be awful before I insulated the garage and got the heat pump installed.