Actually it's not true that FIDE titled players have to provide their real names to lichess. That would only happen, if they want their FIDE titles displayed in their profiles.
I don't agree about the part about identification.
If someone want to know his/her opponents in person, he/she could still join a local chess club.
The function mentioned in #5 should be sufficient.
What, my idea is the best idea, I'm leaving Lichess if it sin't implemented in the next 3 weeks!
There are alternatives to requiring an ID. Phone number verification is one. It's harder to get a new phone number than a new IP address and importantly it costs money.
Well my thoughts are that people post their real names on facebook to see, which I don't understand why. So why not on lichess. On lichess you could have the option to make your name public or keep it private.
I don't think limiting accounts by ip method works very well since a user can use a virtual private network. If lichess could limit the accounts created by blocking the virtual private network then I guess that alternative is better than having to provide id to create an account.
I'm not sure if phone number verification is a good idea since people could make multiple gmail phone numbers through google voice.