This is all strictly opinion and I will be playing devil's advocate quite a bit here.
The first point I would like to make is this, it is pretty unfair to always expect other players to remember the details of your RP. Sure, the people you are around a lot and you RP with often are going to remember it, but the people you meet once? Or someone who drifts through maybe once a week? I know RL at work I prefer to be called by the shortened version of my name, and every I work with does that, but the vice president of my division calls me by my full name, because that is what is on my emails and business cards and that is the main thrust of the exposure he has to me. In my opinion, people forgetting that you just go by the shortened version is going to be the price you pay for that particular RP line.
Not greeting is something that has been a topic around here for a long time, but let me put it more in to an OOC point of view from the players, rather than the characters. You choose not to greet people, people accept this at face value and greet you. You now have the ability to do all sorts of things like using the amulet of communication any time that you want, using long distant magic, using target travel spells, they do not have that ability in return. You can call them up and ask them for help any time that you want, they can only ask you for help if they can physically find you, without magic. From the player point of view, I would really resent someone who calls me for help or even just to chat, but offers me no chance to do this in return. I might resent it enough that I would simply refuse to RP with the person, particularly if they do make a habit of calling me when I cannot call them.
It has been a common complaint that the amulets of communication are treated more like cell phones that items of magic that use telepathy, and frankly I really wish they had an off button or that they could be gotten rid of completely and replaced with spells that could do the same thing. As I understand it, the amulets of communication ICly work through telepathic magic. One reasoning for not being able to contact someone who has given you a false name is that the magic gets confused when you try to telepathically reach out to that person. As the code requires that you have greeted the person, that magic must be based somehow on name. I try to reach you, I cannot, there must be something weird going on, as the amulet focuses on name, it must be something weird with your name. To me, this is a perfectly logical chain of thought.
The amulets themself are not a Forgotten Realms thing, I believe they are something inherent to the codebase we are using.