Do people really think it was a good idea to use the parachute in this case? I am not convinced.
I think in this particular situation it probably was '6 of one half a dozen of the other'. It shows how gentle a 25 knot splash down speed is, no danger of submarining, rolling over, etc. with the upside of the ability to get out above the water and inflate the life raft on the wing.
The ditching speed of a 172 will be about 50 knots (so into wind the same gentle arrival). However, on a day with only 10 knots of wind, the sr22 will splash down and not be towed into the water by the chute (hence a virtual certainty of stepping into the raft dry), whereas the non-parachute plane will be sliding into the water with 2.5 times the energy, which may be sufficient to risk submarining, flipping on contact, or stoving in the windshield and flooding. This is not to say these always happen, but there is certainly a reasonable frequency for people who have ditched to need to extract themselves from an upside down, or water filled cockpit.
Having watched the video, the only reasons I wouldn't prefer to parachute in would be, 1 - an issue at low level so I couldn't count on being deployed into a level attitude, 2 - ditching in winds over 30 knots where you are going slower flying than floating. I am struggling to see the significant downside on a low wind day. If it is blowing 30-40 on the ground, then I can buy the very significant downside of not comming to a stop when you ditch, but being dragged around.