We all know gnomes, don't we? Well, them little fellows are called fighter/illusionists, should they study both the ways of steel and magic trickery. That multiclass name appears on all GUI screens. Likewise, if a human necromancer (e.g. Xzar) decides to become a cleric, he is then called a cleric/necromancer and this name appears on all GUI screens.
But what happens if a Kensai suddenly becomes interested in magic and changes his occupation to mage? Well, he's called a fighter/mage on GUI screens. This is the case with all non-mage kits.
What I would like to see is the dual- and multiclass kit names displayed properly, as with mage specializations, meaning stalker/clerics, berserker/mages, fighter/assassins et cetera.
To sum things up, whilst this is not a vital feature, it's one that would be nice to have. Last but not least, both power gamers and roleplayers would surely like it, the earlier for significantly enhanced readability and the latter for even deeper immersion.