I don't see an issue with companies like Tesla wanting to retain the old parts to be able to refurbish and replenish aftermarket parts for service supply. The more parts that are made available to be reused in a safe manner, the longer the cars will not go obsolete and lack parts in the future. Although it varies across countries, the legal requirement for supplying spare parts are 7-15 years from manufacturing. Nothing stops a car manufacturer from trying to keep this longer so it's a sensible and cost effective way of doing this. I'm sure that many of us Tesla owners want to continue owning our cars for many years to come so...
Instead, be happy that Tesla has a great interchangeability of parts compared to many other brands where parts are changed every year and thus starting the clock ticking for parts to become obsolete.
That's how I see it anyway!