This would be a low priority for me. As krellen mentioned, your core party is role played by you. Nothing is stopping you from playing husband and wife, siblings, cousins, etc. and I've done as much in the past. The need to make this an affirmation via a character creation mechanic does not feel necessary to the game.
What is more compelling is to have background mechanics in character creation that have direct consequences in the game
with regards to interactions with NPCs, quests and locations. I would put more priority on that as it enhances game content.
This feels more like a crutch to role playing, but I can be convinced. Show me how this would increase game immersion (beyond party banter, I tend to provide my own party banter in party-based CRPGs
) and I may change my tune.
(edited with a bit more explanation)
By reading the post u linked, It actully reminds me about the 2 background choices u can pick in Mass Effect 1.
By choosing Shepard's birthplace and event in previous army life leads to different quests, dialogs.
Increase the replayability and deepen the plot.
It's actually can be done with the relationship system I have done...
but this time.. the quests are not only related to one ranger in your sqaud with NPC or the world,
but also the other ranger who has the relationship with you.
This can leads to strengthen the "buff" between the two, "debuff" or new items useable only with the two
(hell, even items can be used only when the two are close to each other or far away?...etc).
Quests can be someting linked to the past, or new events challenging your relationship.
and this system can coexist with those archetypes.. so its like a mixture of things
you have ur career background but also an extra interaction with your own squad.
eg. having a sidekick doctor who can heals you more than other guys in the group.
have a quest to help your sidekick..blah..blah..blah..
So why do I want this relationship option?
I mean "ye, everyone can play their own characters' banter or relationship in their own mind". But truth to be told, not every1 can play minecraft at the start and have fun with it...not every1's "imagination" is on the same page. ye, this is one reason for me to propose such thing. To reach those people who hates the idea of creating 4 players with no interaction, pure slughtering machines and doll-like. You then might say, "this game won't be epic, if it trys to please everyone". Yeah, but I don't think adding such system is a bad thing. Basically, it's a optional setting for the group, it helps deepen the plot and increase replayabilityl. And i can see there are some people in the forum like the idea of having one protagonist as their avatar more than roleplaying four avatars.
the second reason is that, imagination of our own is like playing the game with extra rules of thumb.
It doesn't have "real" value or restriction in game when trying to play that way, and u can easily break it in some circumstances. The relationship setting can "force" you thinking that, for example, those two best sidekicks should be close together in battlefield because the "buff" they can from each other. or even a special quadruple-team killing cam in the end of the fight..(ye i'm joking, i went to far).
So does the setting only affect between the two characters only in the squad?
NO, it will have effect on other team members. It's for sure your best sidekick has more or less feeling against someone who is your rival. More related quests can address that as well. But then, the more you put in, the more workloads for the dev.
It's something I have in mind, I don't mind creating my own party. The setting can emphasise the feeling of "band of brothers"(well, at least for me
). If you think the idea is still something at the level like wife, husband, cousin or whatever setting you can do in you own brain, then I'm fine with it. After all, I'm just throwing ideas during my holidays.
(keep my brain functioning, not drinking and killing braincells)
May think to expand more on this setting, but It comes with time