Honestly I think it is the addition of needing a passport that is the reason for the decline of Spring Breakers
Before the need for a passport there were MUCH more Spring Breakers.....I avoided that time of year like the plague
But just like Rob says, that has definitely not been the way much anymore....nothing at all like it used to be and nothing at all to worry about either

My first trip to Jamaica was actually booked through a student travel service....now they catered to Spring Break packages but of course I didn't go during that time, but I remember they had some pretty good package prices...of course that was in 1999 when Spring Break was in full gear in Negril....crazy crazy times
MTV, Taco Bell trailers....tons of crazy parties

And of course it may be that we live in Florida but for us, in the last couple of years or trips to Negril have been our cheapest (AND BEST) vacations