I think one of the big problems is that not everyone feels the same way (understandably) about the Scions. Not everyone feels like their WoL is super best friends with them, but it seems like the writers are afraid to put any of the Scions truly at odds with the WoL perhaps out of fear of alienating people that like particular Scions... which is probably why the bait about Scions vs Scions in DT ended up being a fakeout.
Rather than continually trotting out the Scions every two seconds into the MSQ though, if they want a character that feels connected to the WoL on the level of a companion they should bring back the concept of the Path Companion.
Back in 1.0 you could customize the Path Companion to look how you wanted and I think there was an aspect of adjusting its personality too.
This wouldn't be the same path companion per se, but make some plot development like this: The Scions are officially disbanded by end of EW, but the WoL still needs help now and then keeping the world at peace, so he/she revisits the Path of the Twelve organization and sees who is still loyal to that group to look for representatives to help him/her keep an eye on worldwide developments. During that process the WoL decides to choose someone in particular to act as their second-in-command, a companion who may sometimes travel with them on missions but also serves as an intermediary for other groups to keep the WoL connected to important events and news around the world.
In this recruitment process, your WoL would be allowed to "recruit" (aka customize) a Path Companion, customize them like you would with a retainer and select one of two or three personality traits to affect their speech. They should also have voiced lines in relevant MSQ missions like any other NPC, which would require a few variations, but in the grand scheme of things a character like this that the player has such control over creating would be ideal and would let us make someone who we could feel actually was a true friend of the WoL, rather than a bunch of Scions we are forcefully friended to with no input on their characterization. It honestly makes more sense that we would come across someone like a Path Companion far more frequently than forcing the Scions back onstage every other mission, and it would add a little uniqueness to how we each view our own WoL's personality and preferences through that Path Companion.