The entire argument that hand computation is necessary to understanding mathematics, propounded and supported by Jerry Rosen and Wayne Bishop--among others, reminds me of the admirals of the British Royal Navy during the period following the Napoleonic Wars. Steam, they argued, would destroy seamanship, just as Jerry and Wayne now argue that computers will destroy mathmanship. (It's a poor word, but a good parallel.)
In point of fact, steam did destroy seamanship--as those old seadogs understood it. But seamanship is alive and well today. That's because the new technology changed the nature of seamanship.
If the goal is to bend rope to sail, sail to mast, and mast to ship in order to steal way from the wind, then seamanship is alive only in the hands of a few scattered practitioners; the old seadogs were right. But if the goal is to ply the seas with what speed and safety (and even comfort) one might, then seamanship thrives.
Mathematics will continue. Technology will change its face, and we see but dimly, as in a glass. The same is true of mathematical pedagogy. The question is not whether we should use calculators or computers, for surely we will.