Lets review some issues.
Single lifting source (envelope ) no redundancy for rupture or failure.
Single burner, no redundancy.
Highly explosive and flammable fuel source (Propane)
Open basket with no energy absorbing seats or restraints for passengers/crew
No control of direction of travel except prevailing wind at various altitudes. theres many more problems with balloon's but I think those above are the major flaws.
Or we could simply read the investigation report:
"The basic design and safety of the balloon were adequate and improvements in the design would not have altered the outcome of this accident. "