|via Wedding Bee|
Touching the bride's dress was considered good luck and managing to snag a piece of the dress was considered the height of all luck. So, guest began to rip pieces off the bride’s dress while she was still wearing it. Clearly this started to become problematic...and a little risque.
Since having their dress ripped to shreds was not something most brides wanted, they needed another idea of something "lucky" that they could throw into the crowd to keep their single lady friends under control.
That is why the bouquet toss was born! Nowadays there may be a mad rush to catch the bride's flowers, but at least her dress is out of harm's way! (source of bouquet history-isms)