I don’t think there has been a conscious effort to do that, I just think it’s a natural outgrowth of John Byrne’s NAMOR series from years ago. That’s how many of the creators of today first encountered the character, and so it’s how they think of him.

Plus, there’s been a movement to have characters refer to one another by their regular names more often rather than their super hero names. It may just be something in the zeitgeist, a feeling that the super hero names sound silly in conversation, but you’re more likely to hear about Tony and Steve and Bruce than you are about Iron Man and Captain America and Hulk. Namor is Namor’s name.