This is one of those sticky statistical questions. In general, people are rarely struck by lightning. However, part of that is because nearly everyone is in a building or car these days. People who work outside are much more likely to be struck. Also, most of these statistics are taken nationwide. In many states there are no fatalities because there are no thunderstorms. So since you live someplace there are actually thunderstorms the rate is significantly higher than the national rate.
Note that at airports as soon as there is cloud to ground lightning detected in the airport vicinity all ground works stops. That is, all baggage handlers and everyone else on the tarmac moves indoors. The planes and the passengers are safe, there may even be take-offs and landings still going on - but all exposed human activity on the tarmac stops. Similar for sporting events. There is a good reason for this...
Also keep in mind that while lightning strike *deaths* are low only about 1 in 10 people struck are killed. So there are ten times as many people being struck as show up in fatality rates. While only 1 in 10 die, 8 in 10 suffer a permanent disability of some kind - often neurological or central nervous system related.
So don't screw with lightning. Yes, you are "unlikely" to be killed if you are an "average" American. But if you are someone who spends time outdoors during thunder storms obviously you are much, much more likely to be struck than "average" since you are doing distinctly "un-average" activities.
Also keep in mind besides the lightning itself nearly as many people are killed by falling trees from thunderstorm winds - almost an equal number in fact.
So, wussypants or not? I'd say it is pretty darn sensible to not ride your bike in a thunderstorm. However, does that mean "don't ride your bike"? That depends. Maybe you can have a back up plan for the afternoon commute? Check the weather and radar and if things look bad get a ride. Or have a book with you and wait it out at work. Perhaps some fraction of days you just decide to drive if the forecast is quite bad. And understand your route. Know where there are some makeshift shelter spots along the way, understand lightning safety and the proper stance to take when no shelter is available. Since you mentioned "metal cars" as if they are a threat (they aren't at all) I'm going to suggest reading up on lightning safety.
Taking the above measures I suspect you'd be able to ride your bike a fair fraction of the time during storm season and minimal risk. You might get stuck in a storm once or twice but will be educated enough to know what to do to stay reasonably safe. You might end up with an inconvenience once or twice too (begging a ride, staying at work longer to wait out a storm, etc. etc.).
You have already gotten over the hump of fearing car accidents (much more likely) so I don't think you should let weather chase you away. Just learn and plan in advance.