And, dollars to donuts, the officers were responding to a caller who was complaining about the noise. The officers cannot have their peace disturbed, so it would be pointless for them to complain about noise in the skate park.
I am certainly not annoyed by kids with skateboards - heck, all my boys have had them at one time or another. What annoys most people is the attitude, the noise, and the disregard for others often exhibited by many (not all) skaters. And the actions of those skaters with a 'tude taint the public impression of all of them.
A proper attitude can propel one a long way in life. More of the diehard skaters should learn that.