I'm not saying that their personalities have to be defined by one particular archetype, which is just bad writing, but that it gives a quick way for players to be able to understand something about the character. (And I was thinking Shrinking Violet.)
I'm not saying that you can't give characters quirks or that we have to get rid of all the traits, and only deal with archetypes, but that it gives the player a lot more information in a much shorter amount of space, since it relies more upon how the player already percieves and categorizes the world. You can say "Grouchy old man" and then follow up with "who has strict self-discipline" and "a deadly fear of mice" as further details.
In fact, I think I'm going to have to call you on what you think that dwarf whose set of personality traits I read out means... Let me see if I read the same thing into it that you read into it.
I give my dwarves nicknames based upon what I read in their details menu so that I can at least try to tell them apart, and frankly, I generally just devolve into calling dwarves stuff like "Silverboots" because she likes silver and boots, since the "likes" stuff is far simpler to read. If you can get something close to what I came up with when I nicknamed my dwarf in the game, then I'll admit that maybe you have some point. But really, I am unusual in that I spend much, if any, time at all caring about what's on every single one of my dwarfves' personality pages.
Basically, it sounds to me, that you don't some much want to get rid of the old personality system. But instead you want to add a more easily read and understood personality archetype system.
Instead of saying, "Urist rarely feels discouraged, likes to work, prefers to have work done quickly, chooses not to associate with others." It could say, "Urist is a workaholic with no time for friends." Instead of saying, "Fikod likes to procrastinate, is very creative, likes to makes works of art." It could say, "Fikod is an artist that rarely has the drive to get work done."
It doesn't some much get rid of the numbers and multiple traits, but blends them together in a way that conveys personality quicker and with less though.
But in the background.. Urist still has his values and each still has their effect on him (if any). And Fikod might be a procrastinator, but maybe if the value is low enough his like of art might trump his procrastination and would therefore effect his work. For example, if Fikod was a Engraver, you might find he procrastinates smoothing stone (not being creative or art), but goes to work right away when told to engrave.
Thus, you have an easier to read personality type, but have all potential of the current system.