goodness - dying from a preventable disease, however rare an occurrence, is never insignificant. My friend's ds was a perfectly healthy little boy who had just celebrated his 1st birthday, he contracted chicken pox, and died 2 weeks later. Other children who have had similar complications have not had their deaths recorded as being as a result of chicken pox, but of the secondary infection - so the figures may be wrong anyway.
Yes, complications are rare, but encephalitis, brain damage, Strep A, pneumonia, chicken pox in the lungs, toxic shock, sepsis and infections of the skin, eye, bone etc, whilst not fatal can be devestating.
The vaccine has been shown to be 95% effective (and in the 5% for whom it is not effective, the chicken pox contracted is mild and with no complications), for at least 20 years (and as pointed out earlier - this is only under question because the major national vaccination programmes were only rolled out in 1995)
In the USA pre 1995 there were...
10,500-13,000 hospitalizations, and 100-150 deaths each year. Since immunization the number of infections in the United States has decreased nearly 90%