I think you have it exactly right. Why go to all the trouble to attack something electronically, if you can create the same effect with "ordinary" explosives, or better yet with a little white powder?
As far as motives, I waver. On the one hand, government almost always tends toward "more control" (thus justifying it's existence) and they could just be trying to more tightly regulate the internet. On the other, they might honestly be concerned about the security of our electronic infrastructure, but somewhat badly misinformed as to vulnerabilities. On the *ahem* third hand, corporate America (and specifically the security/AV vendors) may have contributed enough to the right campaigns to induce this behavior. I can't decide which possibility depresses me the most. Also, my sense is that the Hollywood DRM campaign is more down Sen. Fritz Hollings' alley than Bush's, and in any case the music and film industries tend to buy... er, be... Democrats rather than Republicans.
-Steve