The short story is, people had generally lost a "universal" excitement and enthusiasm for the US Space program, and - although incredibly tragic - Columbia was perceived as just another part of "doing business" with space.

The "awe" of a handful of highly trained, modern day pioneers leaving the planet on a spaceship strapped to the back of a rocket had - through complacency- been looked upon as no big deal anymore, taken for granted, and - given the Challenger disaster having already been entered into the program as part of its history - people were not nearly taken aback by Columbia inasmuch as losses were somewhat apathetically accepted as part of the endeavor.

An, "Oh well, that's too bad", cynical mindset had already creeped into the country which was still suffering from 9/11, accepted the invasion of Afghanistan, and was getting up for a war in Iraq.

Also, the world was a much different place than it had been in 1986, and the impact of Columbia was just not a severe when filtered through the way media distribution was far more varied, and less reliant upon a small number of "networks" to maintain a population's focused attention. The variety of ways in which people received their "news" was far more divergent than to had been in 1986 and the general reaction reflected as much.