Nor do I find they happen very often. Nor do I find that the team that attacks an HQ has a coordinated attack plan to take advantage of the Dars now down.
I agree with you on all of these things.
I respectfully disagree that they are of much "strategic" value -what they mostly seem to do in my opinion is make guys who are already frustrated with flying for the lower numbered country that already has territory problems sign off, switch to the other arena, or switch to the winning side. Strategically I think that they are a disaster for the side that's winning, because ENY shoots through the roof as a result of the loss of defenders, so the aggressors are suddenly limited in plane choices - meanwhile the defenders that are left circle around aimlessly trying to find the fight that was going strong before the radar went down.
Based on my experience, I think that if HTC checks the logs, they might find that HQ raids mostly occur at times when HTC would probably prefer to encourage people to fly for the side that's radar gets shut down, and that the loss of radar has a negative impact on the balance for the next half hour or so that might outweight any positive aspects to it's inclusion in the game design.
But I'm not "asking" that it be changed, only that they consider reviewing whether it's having the effect that they would want. I tend to mostly fly for the side that's outnumbered, so perhaps I see it's negative impact more than others do.