I agree that on the face they appear to be a more economical investment for people, and the fact they are somewhat reusable is a bonus. However, as I stated earlier those people who view this as a single use item for dispensable fermenting or hot cubing should think about the environmental factors.
Also, I would imagine most people use their hot cubes more than a dozen times if they are seriously into no chill brewing, so I don't think your statement that people use hot cubes less than that is correct.
Moving on from that, if you look at the bans on single use plastic bags at supermarkets, that came about from the incredible amount of wastage from them. As you are aware you can now purchase reusable plastic bags. Sure, they probably weigh more but I would argue they are more environmentally responsible then the single use bags.
Oh, and if you want to comment about packaging, why do you then have all of your products manufactured in China which is notorious for not abiding by environmental laws, and then shipping it to Australia by boat, as opposed to the HDPE cubes many of which are manufactured here in Australia.
So no, I don't think brewers should take comfort in throwing out these bags as single use items. I'm sure you take comfort in it from a money making aspect, but that's shameful.
Additionally HDPE cubes can be recycled, so can glass and aluminum cans that most beer comes in from the bottle shop, so stating that you think people using single use plastic bags is somehow more environmentally friendly as opposed to recycling their glass bottles boggles my mind. Distilling down your argument:
HDPE cubes get used less than a dozen times by brewers (highly unlikely)
The bags weigh less than a HDPE cube so are better for the environment (false)
People throwing out plastic bladders is better than buying commercial beer in glass / aluminum packing (false)
Manufacturing plastic bladders in china and shipping them to Australia is better than using reusable, recyclable Australian made HDPE cubes (false)