I can't see a problem with it.
We as car owners want the best safety standards we can get in our metal chariots, so why the hell shouldn't F1 drivers and alike want the best safety features they can get in an F1/open wheel design.
Flying debris has only really become an increased issue with the addition of Carbon Fibre, Kevlar and other high tech plastic compounds that have a tendency to shatter in to pieces when impacted. I can remember back in the days of
metal and alloy, when the Indy car officials decided to tether the front wheels to the car, to stop them flying off during wrecks on ovals and causing mayhem in the spectator stands, even the fencing around ovals has evolved in the name of safety, and it works.
The sport of F1 racing has come along way since the days of hero's like Brabham, Moss, Surtees or Fangio, to name but a few. But so has the pace in which these cars travel, and the materials we use, the cars are lighter, stronger and so much faster, and just like the evolution of the F1 cockpit safety cell, driver helmets and fitness over the years, the safety must continue to evolved. If one life can be saved with the introduction of new safety standards, then we are moving forward, if we fail to take action when a solution is required and obtainable to protect a life, then we are just murderers.
Put yourself in the place of Dan Wheldon, Justin Wilson or Jules Bianchi's families, I'm sure they would agree that an enclosed or semi-caged cockpit could of made all the difference, if it saves just one life in 5yrs of racing, it was worth what ever the cost, because you shouldn't put a price on a life.