Your argument applies to almost any electronic product - including the one you're typing this message on. There is of course some environmental impact associated with purchasing and eventually disposing of electronic good. If they are disposed of properly however, they don't end up on beaches in Hawaii.
What about the impact of the very device you used to post this message?
Also, considering the GoPro replaced disposable film camera (really disposable, unlike your overly extended definition) the net impact of Gopro could actually be very positive.
I live in Hawaii and I can see the impact of this (disposable electronics) every day on the beach. What's problematic is not just the waste that is the direct result of this company, it's the fact that nobody is even acknowledging the destructive impact of the company. It's hailed as a success -- and nobody notices the impact on the rest of us?