The problem with this idea is that there are plenty of places in the world where dollars (or anything else with connotations to the US for that matter) are not viewed in the most positive light (to put it mildly).  While I'm sure it would make sense for people in Western countries, we have to remember that bitcoin is a global currency.  It's understandable that most of us in the English speaking part of the forum will have a western-centric outlook of the world and it's easy to forget that people in other places will have radically different views.  Bitcoin at it's core is a neutral and unbiased algorithm, so we should stick with new and neutral denominations.