I don't buy into any of the arguments about intent, or "unfortunate", or whether it was a "true" lift, etc. Nobody can reasonably deny that the actions of the tackler resulted in the tackled player being flipped over.
I'll draw an analogy. Years ago, boots on bodies in rucks was considered normal and "part of the game". Then, 20-25ish years ago, the powers that be decided (rightly IMHO) that this was an unnecessary element of risk, and that standing on players on the ground would be penalised. A zero-tolerance approach was taken, on the premise that players were responsible for where they put their feet. There was a sizeable contingent (mainly of the armchair expert / retired player / the-older-I-get-the-better-I-was type) that bemoaned the death of "proper rucking", but miraculously, season by season, players got better at stepping over bodies on the floor, referees got better at dealing with players on the floor, and gratuitous stamping became largely a thing of the past.
For some time now, we have been going through a similar transition with tackling. The powers that be have decided (rightly IMHO) that players landing with force on their head and neck is a bad thing, both for the player and for the game. So we have incidents like Umaga/Mealamu dumping O'Driscoll going totally unpunished in 2005, but just 6 years later Sam Warburton gets a RWC red card for a challenge half as dangerous. It's a drive to improve player safety, but just like the rucks in my analogy, there's a contingent (mainly of the armchair expert / retired player / the-older-I-get-the-better-I-was type) bemoaning the death of "proper tackling". And the way we will best embed the changes is by making tacklers responsible. There will always be the unavoidable - the awkward fall, the ankle twisted in the turf, etc. - but we can control the avoidable. And sure enough, eight years after the Warburton tackle, most rugby folk now understand that a tip tackle will be penalised.
So to this specific tackle:
- Was it dangerous? Yes - anything causing a ball carrier to land head first is (rightly IMHO) now considered dangerous. And let's be clear, while it may not have been intentional, the tackler (and nobody else) caused the ball carrier to land on his head.
- Was it reckless? I would contend yes. At that speed, from the moment the tackler left his feet, he relinquished any physical means to exert control over the collision.
- Could he have tackled differently? Absolutely. That rocket tackle was a choice, not an accident.
- How do we eliminate reckless, dangerous tackles like this? The same way we removed "a good shoeing" and "a good old-fashioned dump tackle" - with a consistent front that says this type of uncontrolled collision is unacceptable, and if you choose to instigate one then your game is over. And sooner or later, players will choose not to tackle like this.