There is no rightious, questionable, debate of thoughts even, when...
It's the relative velocity of the obiter vs debris that's important, not the rel.vel of those things vs earth. To know how fast the debris was going relative to the obiter, neglecting wind, you have to know the time, or distance the stuff fell(decelerated), both are known, and the acceleration of the rocket. I saw an est that it was about 80-150mph, but I didn't check it.
The debris doesn't have the hardness and density of brick though. It's either foam, or a thick frost layer.
Even if it was ice, it wasn't but 20" long, and would be more like the stuff on the inside of your freezer that hasn't been defrosted, or maybe like a moderately packed snowball made from fairly wet snow, not all that rigid or strong, like the ice cubes in that freezer or ice on a lake. Furthermore even if the shuttle is going that fast, so is the debris when it falls off the tank or strut. So it only falls a few 10s of feet relative to the shuttle, albeit in an effect gravity field of 2-3 gees, because when the ice or whatever broke free, it started accellerating down at 1 g, while the shuttle was accellerating up. Lets assume 3 g and 10 meters ( 30 feet) : the debris would be going 14.14 meters/sec or 46.4 ft/sec relative to the shuttle or just over 30 mph, a far cry from 1000 mph. That's slow compared to a .45 ACP pistol bullet at 870 ft/sec muzzle velocity. And even slow compared to a BB gun or paint ball gun, the latter on the order of 250 fps. The slushy ice might not be much stronger structurally than that paint ball either, as evidenced by the way it went "splat" when it hit the wing.
The shuttle may have been moving in excess of 1000 mph, but remember the "brick" started out moving at the same speed. The actual relative speed between the two would actually be very small. The "brick" stopped accelerating when it broke off and only traveled a small distance before hitting the wing.
Probably a case of "whistling past the graveyard". Previous incidents have not resulted in tragedy -- bringing creeping confidence/laxity? I am curious about one thing: exactly how fragile are these tiles? Surely they are not as strong as ceramic, which wold be very heavy. But they can't be soft-structurted, like foam. Are they fibrous, like aspestos? Do you have any idea?
(Notice from this that your words are the ones which thoughtful FReepers need to "parse.")