Exactly. That is why it's called an opinion. You saying her head is too small is no more a fact than me saying I don't think it is. Sorry, that's how it is.
No, its not really an opinion: I can look at the pix and see that her head, especially the EX head, is just too small and don't even get me started on how her neck is narrower at the base than it is where it meets her cranium.
Objective evidence.
Now, like I said: if you like this, have at it. No one is stopping you, and anything I say should be irrelevant. Just like you telling me "Nyah, is not!" is not meaning all that much to me. I am an artist and have been judging scale by sight since I was too young to understand the concept.