You should not have one arm resting on the armrest.
You should have both hands on the wheel.
Having owned several cars with the exact same problem with a too-short armrest, I know how uncomfortable that is. You do wonder why such things are not thought of. I suppose the designers must all be gorillas. As for driver comfort, however, be VERY THANKFUL that you got the Milan. Overall it is an AWESOME car. My mom just got a Volvo S60 and in driving it last week I was so uncomfortable I don't plan to drive it any more unless I HAVE to. The interior is so cramped that the center console rubbed against my right leg and forced it into an uncomfortable, bent position. And no, I'm not that big. I am only 5'-10" tall.
I was at a Mercury dealership today and happened to look over a new 2007 Milan. I was VERY IMPRESSED. I had already checked out the Fusion and MKZ, both of which are versions of the same platform, but I had yet to look at a Milan.
What threw me for a loop was the PRICE. The one I looked at was a nice, well equipped model with a moon roof, and it only listed for $21,000. I had just looked at a $30,000 Pontiac G-6, and I can assure you the Milan is twice the car. I even like the styling of the Milan better than the much more expensive MKZ. Tough decision, as I had started out considering a Mustang, but with the rave reviews about the Fusion, and its reliability and build quality being rated way above Camry and Accord, I may opt for a Milan.
My only concern is resale, as Mustang will return much more of its purchase price in 5 years than the Fusion/Milan. Sedans are the worst in losing value.