I have lived with a <80% iPhone 6 for about half a year now until i replaced the battery yesterday, i never realized how slow my phone was thanks to the safeguard implemented by Apple.
But seriously, my phone is 4 years old now and lithium batteries wear out, cant expect them to last forever, no-one should, my old battery had almost 1500 cycles during these 4 years and yesterday i extended my phones life for 2 years atleast (although i will upgrade to the next X in the fall) for 29 dollar, the cost of 3-4 pizzas so i really dont get what all the fuzz is about, battery replacement was cheap before too and Apple gave the phones extended lives through software to safeguard the phones from crashing/turning off thanks to low voltage with the old and crappy batteries.
Dont know why some people are upset by all this