Why isn't the player portrait a circle like the target portrait?

Is there a reason that the player portrait has the arrow in the lower right and isn’t a circle like target portrait?
It looks like it is supposed to open a menu but it doesn’t?
Is it just aesthetic?
Been trying to figure out why it is shaped that way and if it is supposed to do something I am missing.

Haven’t used the default frames in ages but it might be for the threat indicator; or to make it meld with the pet frame, if there is one, better; or yeah, could just be aesthetic.