What is the importance of tolerrance level in a capacitor?
VERY application dependent, for instance decoupling capacitors are often -20/+100% and that is just fine; whereas the capacitor in a pi-filter need be quite precise.

Is it so vital that the capacitor may have chances to blow up
if its tolerance level is not taken into consideration?
that may be 'vital' in 0.0001% of cases.

Now, if you talk of voltage, that is another story, but I never saw a 'tolerance' on that, just a max.

Erik