opherben
I have flown with and without AOA indicators. They don't replace airmanship and flying skills.
Computers and all other stuff built in to modern FBW aircraft donīt either, but they are deemed necessary anyway. Because they help and assist to implement airamship and flying skills, as an AOA indicator would do as well.
Otherwise we could argue about what is really necessary besides airmanship and flying skills:
A cup of coffee: When the coffee leaves the cup, you are flying upside down.
And a cigar: When it is finished, itīs time to land.