QuoteSecond is the AI's propensity to just ignore the charges. This one is probably something only Tynan could change, but... setting an explosive out in the open, unburied, in front of a door? Smarter raiders would just shoot the explosive until it either went boom or leaked out all of its 'splodey bits.
It is actually really easy to make raiders target blasting charges, you just need to add one line to the blasting charge thing def, that I have highlighted in bold
</costList>
<researchPrerequisite>BlastingCharges</researchPrerequisite>
<combatTargetBuilding>true</combatTargetBuilding>
<surfaceNeeded>Light</surfaceNeeded>
<designationCategory>Security</designationCategory>
<ConstructionEffect>ConstructMetal</ConstructionEffect>