Funny.....I thought lasers can hurt YOUR EYES! DOH! We have to wear goggles in the OR. DUH. Waste of money unless you want your fish to need Lasik. lol SH
Im sure they covered their back sides with logic such as this... If your tank has X disease, the laser might kill it, which would in turn make your fish live longer, and if your fish is a baby angel fish then it will make it's fins grow longer by allowing it to survive longer...
Marketing scams like this have always existed and always will. It's sort of like survival of the fittest... the dumber ya are the more you waste your money on false claims.
Not to say someone would have to be dumb to buy such a thing. Personally I think it would be really cool to make a smaller (15-20 US Gal) aquarium a retro 70s theme with laser lights and a disco ball