It was the easy option, it did the job with the maximum of effectiveness and the minimum of cost, and we kept using it until we advanced far enough to see where the cost really lay.
That doesnt just apply to plastic either.
The thing is it got popular because it's good, take a look around and realise just how little would remain if you suddenly took all the plastic and it's derivatives away.
The problem is we used it so much it became easier to use it instead of other materials that would have been better suited, or even just because it was the done thing.
Perfect example i referenced in another thread recently is tools, i bought a set of torx drivers off amazon and the package was thus:
-hardened steel tool rods- fair enough that's a good material for a driver
-Plastic overmoulded handles- a good choice, durable, cheap, easily manufactured, immune to corrosion
-cardboard slip advertising the brand and sizes of the torx drivers- why, the brand name is moulded into the handle and the size is marked on the steel rod, so why bother repeating that information?
-hard plastic blister pack- ok, so that was overkill, your using plastic to protect something made of plastic and hardened steel, why? If theyre so easily damaged that a plastic blister pack will protect them then they cant do their intended job.
-massively oversized amazon box- ok, so sure it's cardboard, but wasnt the whole point of the plastic blister pack to protect the item? That would have been enough, and why so massively oversized? Seriously i know you do a range of box sizes and i know that some of the smaller sizes will fit the product perfectly. So why have you send me a freakin microwave box!?
That's just one example, but it's by no means alone. As a society we've become very wasteful, being more prepared to throw away or recycle than to repair and reuse.
Today i helped a freind of mine get a free chainsaw, had been given to him to "take to the dump, it's broken", all we did was tune it and aside from a bit of oil and blade wear it's ready to cut trees for years to come.
But what got me there was the carburettor needles, they werent screws, they were round flat pegs with a single side ground off (think of the shape of a transistor), and as such it was a massive pita to adjust them by jamming a screwdriver into the gap between the flat and the housing.
And why was this done? To stop people messing with it, so that most people wouldnt bother trying to re-tune it when it eventually needed done, so that they could sell you a whole new chainsaw or charge an extorsionate dealer rate to fix it.
Once again, its not just woodsmans equipment, its everything from mobile phones (remember when a screen replacement could be done in an hour with nothing but a flatblade screwdriver?) To washing machines or even your car.
Recycling is better than throwing something away, but better yet is not throwing it away in the first place.