I'm not rocket scientist, hee hee, but to my knowledge they only put more cameras on it so the astronauts would know they were in deep doo doo.
There were many subsantive changes, not just enhancement of observation capabilities.
http://www.nasa.gov/pdf/112301main_114_pk_july05.pdf <- 8.9 Mb PDF "Press Kit"
With regard to changes in the wake of the Challenger disaster, which was traced back to seals between sections of the solid rocket motor boosters, there were plenty of design and "decide to go" issues in addition to the asbestos. The mechanics of the seal (the "rigid" parts that house the sealing materials) were radically redesigned.
In both cases, the risks were pointed out to NASA management in advance of the loss of life.