How many electronic devices are used beyond, say 20 years at the outside? ...especially computers? Most devices are obsolete in 5-10 years. I think long-term life is nearly irrelevant for the majority of consumer electronics.
You have to look at the cost to produce these things. Foundry costs are hugely expensive whereas the cost to build PE circuits is rather low. Because you can make these things without huge capital costs the disposable aspect of these becomes more attractive.
The problem is that I doubt "plastic semiconductors" can be made to last even 5 years. Plastics are NOT hugely stable (with some exceptions). They have to have all sorts of additives to stabilize them.