Literally the first time I saw that car I thought "oh, because Ford bought Aston Martin now they're going to steal styling cues?"
Granted, they no longer own them, but they did at the time this was designed. Obviating any of the trademark / trade dress issues.
Now, you may say [rightly] that this doesn't look quite like an Aston Martin. Of course not. It's a 4-door family sedan. Literally it can't look like an Aston Martin for the reasons someone specified--it has to be a practical automobile.
But now that Ford no longer owns Aston, my guess is that they're not going to copy Aston. They have their own designs for sporty cars, like the Mustang, which sells brilliantly. And for supercars, they've got the GT. Which is a niche car, to be sure, but it harkens back to their GT40 while bringing in modern style and technology.
So the answer is... Why would they make an Aston Martin clone? They're Ford, not Aston Martin.
I wasn't even thinking about a time when Ford owned Aston Martin, in fact I'm not sure I knew they ever did.

But my response to your final question is, "They
could make a car that looks like an Aston Martin, because there are many people (other than me) that think the Aston Martin is beautiful, but can't afford it, but would totally buy a reasonably-priced American car that is also more reliable than an Aston Martin."
Before all of the weird side-tracking, that's my only observation-- why don't they make a car that is styled similarly, but affordably priced?
There are some potential answers I can think of off the top of my head-- Americans don't like that kind of styling. Or Americans don't like actually driving cars with less-than-ideal sight lines (although sales of Mustangs, Challengers, and Camaros might belie that possibility). Or "Americans don't like stylish-looking cars with zero or little back seat" (but again, the American "sporty" cars that do sell well, have similar issues).
One other thing, in re-reading your posting of my initial comments, I see that I stated "look exactly like a Ferrari or Aston Martin." I suppose that must be where CD took me literally, and that certainly wasn't my intent. I meant, cars with similar Euro-sportscar lines. As opposed to American-sportscar lines, of which we still have several examples on the market.
I'm not sure
why he decided to take me literally, I'd certainly give him enough of a benefit of the doubt to assume he is smart enough not to imply an IP violation. But there you have it.