Hey Diamond*Girl,
I think the biggest problem here is the fact that the product was marketed to the group as "GREAT FOR KOI PONDS!"
There is a local koi club member in my area that is a big fan of his floating islands. He actually has them positioned above his air-drains so the bubbles are captured and contained with in the radius of his floating islands. In doing so, he actually has a better viewing area for his Koi. Other wise the air bubbles would disrupt his view.
He is actually using fishing line!

It is always hard to hear about that rare percentage of accidents that happen. The fishing line was of course used to be less visible for human viewing. As you pointed out, I am sure there are some other creative techniques for anchoring the island that would reduce the possible danger of injury to the fish.
To qualify this koi hobbiest: His pond is approximately a 20' x 30' x 5' deep, two bottom drains, nexxus system, W. Lim Wave 36 settlement tank, u.v. etc. You know, the works and his collection of fish is SEXY to say the least. This pond would certainly qualify as a Traditional American Koi Pond.
The Pond Digger
P.S. By the way, love the name D*G..........