You haven't convinced me this is a good implementation of the idea.
I don't think that remembering people by numbers intensifies gameplay, and it gives even more power to back-stabbing thieves and killer than they have in real life. If someone tries to kill me in real life, most of the time I can reasonably identify him which can lead to his capture... I see no way how this is accounted for in your idea.
The idea was not for people to remember others through a number, if you decide to become friends, you would know each others name. Like I also said previously, introduction would not be necessary as you have the option to flag someone until the string changes. Back-stabbing thieves (here I assume you mean people who pretend to be nice but then kill you in the wastes), cannot be avoided currently when you know a person's name. Your best bet with this system is to travel with people who introduced themselves, therefore you are not better or worse off relative to the current system.
You are saying that killers are given more power, with this system than the current, well lets look at plausible scenarios and see how much power if any do they gain.
- Current: A PK gang has control of a town (can be checked on PipBoy), and when you use Town Preview, you see well known PKers. You probably would not enter the town.
New: A PK gang has control of a town, and when you use Town Preview, and you see random players you don't know. Realistically you still probably won't enter the town.
- Current: An Anti-PK gang has control of a town, using Town Preview, you see well known Anti-PKers, so you decide to enter the town. Since you are not A PKer you do your thing in the town.
New: An Anti-PK gang has control of a town, using Town Preview, you see random players (though heavily armed). Now it could be two possibilities, one, is that it is the Anti-PK gang, or two it is some PKers, causing trouble. If, two happens and you die, well, you can tag them, and for certain amount of hours you know there are PKers in the town upon using Town Preview. Now, lets say one happens, you have a chat with the Anti-PK gang and introduce each other. Next time you enter the town, it would work like the current system, maybe there will be new people you don't know, but you can introduce each other so it isn't a problem. Now when ever you see random heavily armed players in Town Preview it is a good assumption that they are PKers.
- Current: You meet a person in the mine (or the wastes), who is armed heavily, you don't know, so I am assuming you begin running away. Three possible options here. (1) He manages to kill you, so you add his name to name colorizer. (2) He shouts "I am not PKer", when you go back he waits for you to mine, then kills you, you add his name to name colorizer. (3) He shouts "I am not PKer", you mine in peace and leave.
New: You meet a person in the mine (or the wastes), you don't know who is armed heavily, so I am assuming you begin running away. (1) He manages to kill you, you tag him for future reference if you decide to come back into the mine a little later. (2) He shouts "I am not PKer", when you go back, when you go back you ask to introduce himself, if he says no, you peacefully leave the mine, if he says yes and kills you after you mine you add his name to name colorizer. (3) He shouts "I am not PKer", you ask him to introduce himself, he says yes, and you mine in peace, next time maybe you introduce yourself to him, if you see him in the wastes.
As you see, if you die, you die regardless if the name is hidden or not, and it would be difficult only in the beginning when you don't know as many people. If you have more scenarios that I might have overlooked, mention them.
Impersonation could be avoided to some point by forcing automatically generated names, which would add to RP even more.
Recognition wouldn't involve grind, there could be a way one could give his ID forever to someone, like a photograph, but what my idea is about is (mostly undesired) disclosing of your ID to your surrounding depending on your actions.
Yes, I see nothing wrong with this, if generated names would be implemented, however that is up to the Devs.