That only changes the question to "are these products worth it?". I would argue there is a huge portion of consumer products that only use plastic because it is cheaper and the negatives of plastics were not in the equation at all.

Remember, that plastic is not just cheaper -- it's also often lighter. We could do a lot of stuff with metal, wood or good old granite, but emissions from manufacturing transporting all those heavier goods would spike and we don't want that as long as manufacturing and transporting are dependent on fossil fuels.

Plastic is fine. It has it's uses, and we won't get rid of it anytime soon. We need to get rid of the bulk of the one-time use stuff though, and focus on re-usable items if we want to change something.

I agree, your last paragraph is how I feel about the situation summed up. It is an excellent material, but we waste it on single use expendable items that we could really do without.

I do want to add though that if we had greener transport, then heavier items wouldn't be that big of a deal. So if we are playing the long game, that would almost be a good incentive for transport and industry to be more efficient in the long run.

But what would you be using instead and why would that material not have broadly similar negatives?

It vastly depends on the product, but it is a question worth asking over and over again when we design products.

It has historically been plastic because it is cheap and readily altered to match the exact needs of the product. Rigid, soft, rugged, smooth, coarse, we can make a plastic suit.

Plastic cups are a good example, we have numerous materials at our disposal but we make disposable cups and containers out of plastic. Even bio-degradable plastic cups are a bad choice of material, as they take special circumstances to break down that many municipalities don't provide for and most users aren't carrying their bio degradable cups home to put in their compost. If they end up in the ocean, they will last just as long as other plastics. So that is bad product design, it doesn't take the full product lifecycle into account and ignores even it's typical usage of just a single serve drink used once.

Plastics have spoiled us too, so in many cases there probably isn't an alternative that is just as good. We may just have to accept that and find ways to make better materials out of more sustainable sources.

Yes - I've also heard criticism of bio-degradable plastic cups from environmental groups.

But, I missed it if you said it - what material should we ideally use for disposable cups, currently?

I would personally pick paper for single use cups. It is not perfect, still quite resource intensive to make and still unlikely to be recycled properly. But they can at least be sustained through sustainable forestry and the waste will degrade in the most likely places it will end up.