It sounds like they didn't like bottle rockets/fireworks, and needed an excuse to get them banned.
It sounds like legislature did in the bottle-rockets. And people probably actually voted for the legislators.
They could have just as easily banned the wooden shingles, after all... Or treated the wooden shingles to make them fire retardant. Or made it law to use fire retardant roof coverings.
After all, there are many ways for a dwelling to catch fire, and bottle rockets are probably responsible for a comparably small percentage of torched homes. To ban them for that reason, would seem to set precedence for banning other things with an equal or greater chance of igniting a house. A candle for example. Or electricity. Or gas/charcoal grills. I'm curious now, is grilling legal in Plano? Are candles?
Where I live, they even make clothing that's fire-retardant, pass laws to make folks' (kids at least) bedding and clothes fire retardant, and make laws to make human dwellings pass fire codes.
They also make it illegal to purchase, sell, or ignite "flying" fireworks, unless you have a special permit (which they give you when you ask for it, pay the several dollar fee, and fill out the form).