I like the use of the new technology for practical things like mast inspections and of course they are awesome for video and photography. I can understand some boaters concern for hazardous falling objects that could injure someone or damage a vessel, as well as general annoyance.
To set your mind at ease (if you are worried about the falling object part), most of the drones have pretty advanced onboard computers (gps and gyro combo) that control flight and crash avoidance. They can automatically return to 'home' when they lose connectivity to the transmitter, fly home and land when 'bingo' on fuel (battery life), elevation or 'ceiling' can be set, etc etc. Most of the more advanced drones are flown by laptop with maps and waypoints, joysticks as a back up only. There are a number of ins and outs, system configurations, and you'll still get 'pilot error'... I guess it boils down to knowing that what is in the air is actually a computer controlled flight capable 'drone' or is it a toy controlled by an amateur with a joystick transmitter. If its the latter, yes I'd be a little concerned of the falling object hazard.
As far as being annoying, I can't help anyone with that... I think the benefit out weighs the minor noise pollution.
How do I know this? I had a pretty nice drone about 3 years ago. I lost it because I was stupid, I was flying on manual without the Nav module installed. After enjoying numerous flights at no more than 20 ft high and 50 ft away from me I go a little too brave and went about 70 feet and starting catching heavier cross winds. Eventually I got disoriented and lost my point of reference (the drones are totally symmetrical). Long story short, I couldn't get my bearings and the drone drifted farther away until I lost transmitter connection and the drone just flew off into the sunset. That was a $800 carbon fiber drone lost somewhere on a mountain side. That is exactly the scenario where the 'go home' feature of the flight computer would have saved my biscuits.
For the purposes of this discussion, since I am pointing the finger squarely at myself as an example, at least in my situation I was flying in the middle of nowhere (AZ desert), with no one or nothing to harm. I did go looking for the airframe on my dirt bike, I never found it... brutal terrain.