Rarity is certainly a big factor even from an objective viewpoint. Concorde instantaneously went from the safest airliner flying to the most dangerous with that crash, just because it didn't fly much. Flying on a Space Shuttle was one of the most dangerous activities out there, judging by the historical failure rate.

It helps just in terms of grabbing your attention, too. "Man drives into lake" doesn't make the news. "Man drives Bugatti Veyron into lake" does, just because the unusual car makes it more interesting.

In the case of Concorde and the Shuttle, the machines in question were not only rare, but beloved by many, and seen as a national symbol. It's almost like assassinating the country's leader.