Even a bean pole wou;dn't work. If you look at the artcile at the official site today they have rather a lot of pics of Michonne Bourriague and whilst she's no porker, she isn't a bean pole either.
I think the term is well proportioned. Every thing in just the right amounts, in just the right places.
I can't think of a reason why they would want to. I heard that theres atleast one project where they are doing that and it's supposed to be really good CGI but I think alot of the problem with that kind of thing is that we notice subtle things about a human that makes it look fake where as we'll accept a little less from an alien because they don't really exist. CGI should really only be used to do things that otherwise just couldn't be done...it takes alot of people alot of time to get a good result with it...and all those people are on salary (even though from what I hear it's not always a good salary...)