I think it would be a good idea to clearly spell out the point:
When you take a catastrophic weapon like the Fat Man atomic bomb and convert it into some fun, kiddie version of itself, it belittles the original horror. It would be like an anime of The Holocaust, except it's a super-deformed Adolf Hitler giving wedgies to Jews. Yes, it may be funny and entertaining, but it's also incredibly tasteless and belittling to the initial suffering that was caused.
Am I hitting close here, Jeans?
As far as HK-47, that's a bit of a stretch. Yes, the AK-47 assault rifle and all of its offshoots are the most efficient assault rifles ever produced, but I feel the weapon itself is completely separate from the damage and suffering it caused outside of its initial scope. That would be like being upset at Jack Daniels for all the battered spouses.
And before someone calls out on the two-faced nature of damning the Fat Man bomb on one hand and praising the AK-47 with the other, I would remind them that the AK-47 was designed for the purpose of being used by soldiers in a war against other soldiers. Both sides know that death is on the menu. The Fat Man, however, was designed to kill indiscriminately over a very wide area and was targeted against a city ful of innocent civilians.