I think I've said this before (maybe that World Trade poster - forgive my memory) but I don't think stuff like this is really a big deal. It made alot of people sad when it happened, and that feeling lingers for alot longer for some people than others. That is not a good reason to not use an image.
This image is not unlike the Hindenburg crashing photo (iconized and over-used) or Titanic references or napalm Vietnam video clips or atomic bomb mushroom clouds over Japan. Those images clearly represent needless and tragic death (often on a much larger scale than a handful of astronauts), but nobody says "boo" about it because the events did not happen in their lifetimes.
I'd love to get my hands on the bastard that came up with the "numbers as letters" thing (3=E, 1=I, 2=Z, all that crap). Annoying and cheeky and misused. Though I can't fathom if there's a right way to use em.