I hear what you're saying about the warnings all such. The reality is that most of the problems that they are talking about have occurred in Mexico City and some of the other big business towns. The organized crime you're talking about, from what I understand, has been known to target wealthy businessmen or the children of wealthy locals. They are not interested in beach-going tourists.
I've been to Cancun and the Riviera Maya 3 times in the last 8 months and have never had any kind of problem, never felt threatened, and frankly never felt uneasy.
Yes, you're going to an economically challenged country. Yes, there is poverty. But the likelihood of anyone associated with your wedding being the victim of organized crime? HIGHLY, highly unlikely. A pickpocket, or an unethical vendor, possibly. But you'll find that in New York, San Fransico and pretty much anywhere in between.