Note: I don't know if this is true or not, and I don't know the performance capabilities of each aircraft.
https://nationalinterest.org/blog/buzz/meet-2-stealth-fighte...
The X32 performed worse in range/payload capacity, Boeing had lots of difficulties developing STOVL on the platform, the delta wing design was less efficient, and Lockheed was still riding high on its success with the F22 program (which no one has really bothered competing with decades later) so it's unlikely that aesthetics were the deciding factor.
The X32 competed with the now-F35.
The YF23 lost to the F22.
I still think the YF23 is utterly gorgeous and I wish it had been put into service.
EDIT: beaten to the comment by 3 minutes. Oh my poor pedantic soul.
It is, but so is the F-22 and because it was a one or the other choice, I personally like the direction they went.