Well Rich Lee have you not ever done circuits/patterns, or an approach over water to a pad/airport which is perfectly legal & regularly done?
Yes I have. In my younger days I even used to ferry long distances across water in a single engine helicopter without emergency or fixed floats. That doesn't make it right. Now I would probably insist on floats if I needed to fly over water in a single engine helicopter.
Or what if the floats fail to deploy
Good question. Of course that begs all the other questions like what do you do if the hydraulics fail, or if the controls become stuck, or if the pilot panics, or electrical system fails and the battery is dead and that causes all the electronic displays to fail, or you are in a sea state that cause your blades to hit the water before you land, or you can't align properly with the swells? All perfectly legitimate questions alone or in conjunction with each other. Secondary and subsequent failures of multiple systems do occur, but I would still rather have properly serviced floats as opposed to none when flying over water.
The bottom line is you do what you can do get the aircraft into the water at a vertical descent rate and horizontal speed that allows the best survival opportunities. I am a believer in following manufacturers recommended procedures. If you are in an aircraft with a transmission that wanders about when the blades strike something, and a manufacturer like Bell says to roll the helicopter a certain way, then do what Bell tells you to do. You can't be faulted for doing what the manual tells you to do.
There are plenty of legal operations that fly over water without floats. However, do something within legal boundaries doesn't mean one is always exercising the best possible judgment. Imagine the case of a pilot carrying passengers over water and the engine or engines fail. Imagine the pilot did all the right things but the passengers drowned, what would the pilot's justification to their families be .... 'it was legit'? Please do not get me wrong. I am have been involved in operations that were perfectly legal and standard operating procedure only to realize years later that there were safer ways to do things. I have learned that there is a safer way to fly over water and that is to do so with floats. With or without floats, every passenger should be briefed on how to exit in a water landing, and how to use personal flotation devices; and they should be wearing those personal flotation devices.
If I made a decision to accept the risk of flying over water in an aircraft without floats, I know that in the event of an engine failure, I will fly the aircraft all the way to the water, and on the way down I will make sure I have a door open. I will use full collective on water entry to dissipate as much main and tail rotor energy as possible. If at that point I have enough control power in the main rotor to roll the helicopter, I might make the attempt if that is what the manufacturer recommends, but I really wouldn't expect too much from the rotor at that point.