This is the only remaining compliant that might has some weight to it. It does make sense though both in gameplay and story-wise. In battle the distance between Noctis and the others decides what skill are available to use, as the director said, the battle system is revolving around the main character. Story-wise Noctis is the only one with magic and special skill.
Still, it is an acceptable complaint at least.
It is precisely what you first wrote what's most disappointing about Noctis being the only PC; just think for a moment of the possibilities using the same battle system but with other team members.
Yes, you could be right, but that might be extremely complicated and unplayable, this is an action RPG not XII. We need to try the system ourselves to sense its depth.