This is something I'd also like to see.
Too often the players are just glued on top of the world created, with little or no way of affecting how it is.
Of course this'd mean quite a horrific amount of extra work for the developers. Furthermore, it should not be easy to make permament changes, especially for one person.
But just that the chance existed, why, it would give many players a real goal to strive for. Instead of just awful grinding and level gathering.
Edit: I forgot to comment on "The Master Lives"
Now, who would carve such a thing on a table? It also pictures a heart pierced by an arrow and the name "Harold", a name we all recognise. Who would carve such things on a table? Someone who knows about The Master in the first place. Harold is a more public figure, as such I'd not pay too much attention on him in this discussion. But only a handful of people actually knew of The Master. As such, the first thing I'd reckon is that the writer is a mutant, the Vault Dweller, or one of his companions on that trip. On the mutants, I can understand they wouldn't be too happy about their Master dying, and could still think he lives, like many do think Elvis lives. It most probably isn't the original Vault Dweller, lest it be between Fallouts 1 & 2, during his lonely travels. And still I can not understand why would he be writing "The Master lives" on a table. Furthermore about the theory of the character in the teaser possibly being the original Vault Dweller, the one sending the postcard could very well be one of his comrades he met on his travels (the wide traveleld Tycho, or perhaps Ian).
But that goes perhaps off-topic already, and I'd deduct the text on the table is written by someone who reveres The Master, and that would most certainly exclude the original Vault Dweller and his companions, and as such, I'd say it was written by a mutant.
Other than that, I'd say it is a joke by the developers