Yes it can be dangerous, but generally not immediately disasterous. A hard tail strike can bend the frame and pop some rivits. If a pressurized part of the aircraft is struck, then the pilots will soon know when their pressurization systems start giving funny readings, and they can turn around. Otherwise, if the tailstrike is not properly fixed, the bent components and popped rivits and welds will cause rapid fatigue and possible failure sometime in the future. I have never heard of a tailstrike causing a disaster on the same flight. The important thing is that is reported and fixed.
The JAL 123 accident, as I recall, was caused by some damage done previously to the tail (I think it was a tailstrike). The repair job was not properly done, and the new rivits were put in places where they would fatigue rapidly, which is eventually what happened, killing over 500 people
Many planes have some sort of rudementary tail skid, made of hardwood or maybe metal. It will protect the plane from damage from very slight tailstrikes, but generally, if there is a tailstrike, however minor, the airlines are required to make a close inspection of the tail.
The only thing you should feel when shooting a terrorist: Recoil.