People saying they wont buy an LG again because of the screen have probably in-directly bought an LG screen anyway.
They are generally very good for Screens, used in the top LCD TVs and LCD phones.
I personally will never buy AMOLED, so the only choices I have are with LCD, which a lot of the time come with an LG screen anyway.
There are manufacturing problems with all products. Even a 99.9% success rate on production means that 1 in 1000 screens/phones will have an issue. You build 1 million phones, that means 1000 will have issues - which is why we have warranties, return procedures, etc.