The same thing has happened around here. Im going to say that there is an increase because there is riders out there that have not kept up with the skills over the winter.
Happens every year. If it makes you feel safer then get em. They will deffinately get you more noticed, that is for sure. But it is no guarentee, you may still find the occasional meat head.
I have had no fewer than 4 people pull out infront of me, but I stick to the rules that have done me well over the years.
1. ride like an idiot, only where sensible.
2. when in traffic or where traffic can appear, ride like your invisible.
3. never get complacient, pay attention.
They work for me!