They did NOT say why the occupancy was so low. All of Cancun was pretty dead as they are still realing from Wilma and its the low season.
The waves weren't too bad but Im not a big ocean swimmer (5 feet Id say). All the resorts on the lower part of the 7 will have higher waves. Resorts to the north have Isla Mujeres to help block large waves.
I'd go to Xelha before Xcaret. Xcaret is basically a glorified zoo. Its very hot. Great to do once. The night show is pretty cool. If you stay in PDC I'd got to Xcaret. Since I've been there twice, I wouldn't go back just cause I've seen pretty much all the exhibits etc. Theres not a whole lot of snorkel either...much better at Xelha..
PDC doesn't have as much stuff as Cancun but I like it there too. I stay in Cancun and usually hop a bus and spend a day there.