One advantage to a 45 degree rise stem is that the adapter and stem aren't sticking back into the rider's cockpit like a longer adapter and stem would do. And, heaven forbid, in the case of an accident a shorter riser and 45 stem isn't going to have as sharp and as exposed a pressure point on the rider's body in the event of an impact with the joint of the stem and adapter.
You say you'd prefer the longer adapter and flatter stem from an aesthetic standpoint. That's fine, you obviously like the classic look of the 7 shaped stems of old. But consider that with the extra rise your wife wants and the rather kludgey look of an adapter and threadless stem the "look" will be a clumsy one compared to the svelte look of the old 7 stems. And add on the protrusion of the raised stem into the rider's space and possible impact issues and the shorter adapter and 45 degree riser stem suddenly becomes a lot more "attractive".