"engineer devices to be easily serviceable with easy to replace parts ?"
My Macbook Pro 2012 is an example of user serviceability.
Problem is no one buys such devices today. You can't have thin and lightweight without glue.
And, you all are cheap enough to buy the bare minimum, then stick in all the cheap-and-pathetic upgrades and replacement parts, then blame Apple when it no longer works.
Grab yer popcorn...fools. Doesn't take an Apple employee to understand what you're forcing them to do.