Why do we keep Euphyllia and Hydnophora?

[Lance]

Between my Hammer, Torch and Green Hydnophora I can't count how many corals I've lost to them. Fish bumps coral; coral tips over; lands on one of these three terrorists; dead coral. Grrrrr!
Aside from maybe a big Bubble Coral, Euphyllia sp. and Hydnophora sp. have to pack the most potent sting. I don't know how many times I've threatened to make reactor food out of them.