There's some kind of maturity in the knowledge about multiple materials, or at least enough to have certain variables. Stiffness vs hardness is one of the most recurrent topics, as a very hard material could be easily breakable if it lacks elasticity. Most plastics do not resist well scratches, temperature and tend to fracture with stress. Besides, only relatively rare ones provide protection against electrostatic discharge events or shielding for electromagnetic interference.
It's difficult to understand —from a naive viewpoint— how the industry resort to plastics with a feature list that ensures, practically, breaking the main structure of the device. Thinking for instance in a pendrive, it's absurd to employ a 1mm thick plastic in the structure, with low degree of elasticity and leaving it free, without additional enforcements, since the device is thought to be carried on in pockets, bags, suitcases, and whatever place where the stress is obvious. It almost guarantees that the main structure is going to break, or, if not, it charges to the user the responsibility of taking special care.
Inconveniences that cannot pass like mere nonsense in the manufacturing team, being the one that forgets these aspects. An aluminum body, metal inserts or some other technique to provide durability are also cheap nowadays. This means it's no luxury at all.
Some try then to establish price ranges and play the lottery of a new sale basing their principles in strange methodologies. However, it's lamentable to have an industry that plays this role in general, instead of creating well engineered products, with the right materials, thought to last decades. This means that other evolution needs to take place to claim more sales; with more sophistication than to sell a window with a crystal that breaks with a bit stronger wind than normal. When you analyze that window, you see thought it, and it might be funny, that use of the questionable intelligence, until you remember the electronic waste crisis and the interrelated toxicity that affects everyone. Who are the culprits? Selecting other materials should be fairer.