LOL, are you sure that these former nicknames was a real names in their documents: Poker Player, The Pharmacist, Coolcryptovator, Igehhh, BTC_Bear, Peeps Place, mjglqw etc?
Offcourse not. But not neccessarily it must be real name used. There is other ways how used nickname can link to revealing identity
No, the real reason of nickname changing is a avoiding of scam accusation or avoiding of accusations of suspicious activity
So, you want to say that these users who changed their usernames scammed someone or made something suspicious? That's serious acussation.
What privacy reasons? LOL

If a person left a bunch of evidence about himself all over the Internet, including Facebook and other social networks, and then just changed his nickname on bitcointalk.org, then this will not protect him in any way
If
nutildah will change his nickname on bitcointalk. How will that protect him? Everyone saw his real name on Facebook
Yes, it won't help much. But if they think that it will help, they have right to ask for name change. Or alternatively they can change their real name and start their life from blank page

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