It's not that hard to understand; getting back the wasted spectrum that analog TV (ab)uses today is worth far more to the government than the $1.5B this will cost. It may be being pitched as "cool new tech" but it's really a sensical reallocation of a scarce, valuable reseource.
Now if only there was some way for the government to mandate resource allocation of another kind, like, say, by raising standards for fuel economy.
Hmmm.
/jordan