The only obscene vulgarity a writer can perpetrate in the world of SF is talk about money, the money trail , the ROI : 'oh the horror ! the horror !
A public invention is not just something that is technically do-able, that forte of the non-fisically oriented SF writer.
No, to become truly public it must also be affordable and in some sense, profitable for the society that creates it.
All great SF 'inventions' (as fruitful the SF writers have all been) remain forever private inventions - great in theory but costing so much money that they are impossible to develop in practise.
Not "so much money" as meaning 'greater than the combined GDP of the world circa 2012'.
Rather, instead, as in 'costing so much money that there is too little left to feed and shelter us earthlings and so no government (elected or otherwise) can survive in power' type of money amounts.
This is SF viewed through the doubting eyes of a political scientists, my eyes.
That cold ,hard eyes of "the authoritative allocation of scarce resources" type of thinker : whose first thought, every time, is
"how are we going to find the tax dollars to pay for this - and who will then oppose us enough to surely defeat us at the polls ?"
Substitute shareholders and 'the stock market' for voters and election ballot boxes and the result comes out the same.
But for a right wing CEO hoping to make money on a hair-brained scheme by feeding off taxpayers money, the key to getting at that tax cash cow is (surprise !) our friendly left wing SF writer or equally naff science journalist-cum-cheerleader, both who will open the wallets of the public by performing the necessary charm invasions first.
Films, plays, books, albums all have their critics.
So why don't proposed technological inventions also have their critics?
Yes, gentle critics with forensic audit like claws and the kindly eyes of actuaries in hot pursuit of a flaw ......