Most insurers will actually cover this - we certainly do.
Technically it is an accident (although not in the sense you would normally associate with insurance claims).
Personally, I don't think we should cover it, but if we avioded all claims caused by failure to pay attention / stupidity, then we wouldn;t be paying a lot of claims!
I can't honestly say that I know an insurer that has a specific clause stopping them dealing with this type of claim.
I would also agree that the cost of repair is incredibly high - around �1000, pushing �2000 at a maximum is the norm I see