Electromagnetic pulse isn't the only reason, or even the best reason, to harden the grid. Geomagnetic storms from the sun can have similar, but even bigger, catastrophic effects. The last really big storm, in 1859, would be a severe disaster if it occurred today. It caused sparks that jumped the gaps in telegraph keys. severely shocked telegraph operators and set telegraph paper on fire in 1859. We almost had one in 2012, but luckily it missed us by 9 days of orbit position. The odds of getting hit with a solar storm in the next decade might be over 10%. An 1859 sized storm would destroy transformers all across the electric grid. It would take months to restore service. In the meantime, distibution of running water, natural gas for heating and gasoline to drive our cars would all stop, because all of them depend on electric pumps. The electronics in our cars might be fried as well. Please see the links:
https://en.wikipedia.org/wiki/Solar_storm_of_1859
https://en.wikipedia.org/wiki/Solar_storm_of_2012
http://www.businessinsider.com/solar-storm-effects-electronics-energy-grid-2016-3
https://en.wikipedia.org/wiki/Solar_storm_of_1859
https://en.wikipedia.org/wiki/Solar_storm_of_2012
http://www.businessinsider.com/solar-storm-effects-electronics-energy-grid-2016-3