Why stop there? Why not add a permanent default appearance to match the permanent default name. That way it'll eliminate any illusion that this character is yours, and it can increase the "story" since characters can comment on your physical features ("Mmmmm... red head," said Bull about everyone but a red-haired Inquisitor) the way they couldn't for "blank slate" protagonists that people bizarrely want to fill in the blanks for so they can roleplay for a roleplaying game. 
I'm still annoyed Bull doesn't comment on redheaded Inquisitors. I mean, it's not like you can choose infinite hair colours from a wheel, so they could have just had him say it for the 3 or so reddish hairs in the CC. But that would take effort, and be innovative, so I suppose I shouldn't expect it from Bioware.
On that note, I do wish characters commented on your physical features occasionally. It doesn't have to be overly specific, maybe a mention of your scars, since it doesn't matter what they looks like, just that they're there. Freckles, since that's tied directly to complexion. Hair colour as noted above. Tatoos could be treated like scars. I just think the occasional mention of something about your appearance would help distinguish characters and add some individuality to them, but also just make the game feel more realistic in that your character is just a person with features, instead of - apparently - someone with no features worth noting at all, no matter what
"Is the Inquisitor defined by her... uh... mark?... and not her leadership skills?"
Absolutely not. Yes, it'd be nice to actually have my chosen name used in some way. But I want it to be my chosen name, not something forced on me -- especially since I have a strong preference for gender-ambiguous names and wouldn't want to be stuck with something as bland and explicitly gendered as "Evelyn".
I've harped on this a million times but I'll do it again: neither the lack of a spoken first name nor a detailed backstory are the actual obstacles to having the player character feel more real and personal -- the writers' ongoing refusal to treat them as anything other than one-sided enablers for the NPCs is. Let the NPCs show actual interest in the PCs' thoughts, feelings and well-being, let them be proactive in proving their care and friendship. Everything else is merely a figleaf that fails to address the real problem, IMNSHO.
I'm fine with being called "boss" or insert-title-here or "my friend". If especially close friends come up with a platonic term of endearment, that'd be great, too.
Funny you used that as the example, since Evelyn is actually a gender-neutral name, sort of. I say sort of because what a culture views as a gender-neutral name changes over time, arbitrarily, but originally, it was also used by men. Though it tended to be pronounced "Eve-lyn".
But I agree completely that NPCs should show an interest in the PCs thoughts and feelings, instead of it almost always being the other way around only. Relationships aren't a one-way street. And I like terms of endearment too. As a recent example, Piper in Fallout calls the player "Blue" because of the blue Vault Jumpsuit you start the game in. I thought that worked well. And if certain characters come up with their own, it makes the game feel less impersonal, since it can feel like everyone is actively avoiding calling you by your name or a nickname. Even simple things like Bull calling you "Boss" help.
It's been a while since I touched the game, but the only time I remember anyone calling my character "Trevelyan" was Envy during Champions of the Just, once or twice before and after the headtrip it forces on us. It was kind of jarring actually, partly because no one else ever does it. During the mental attack, Envy itself switches to calling the PC "Herald" like everyone else does, including Cole in the same situation. When the surname is used in a few other cases, it's always as part of a formal address, i.e. "Inquisitor Trevelyan" which is fine. So I disagree, the surname in this game isn't used as if it was the real name.
You're right that it's rare for to even be called by your last name in Inquisition. I actually wish they had used it more, just to avoid being called Inquisitor, or Maker-forbid - "Herald" - as much as possible, and to add a little more variety for playing different races.