The concept of what an outcast is has always been kind of obvious. I mean it's in the name.
The argument of 'whoa, whoa, whoa – you mean if I play an outcast, part of my rp has to be that I'm an outcast?' is a bit like saying, 'Whoa- you mean if I play a Slave, you mean I have to be enslaved to someone(s)?'
It was always kinda on the tin, and I think the team always presumed and hoped that people would respect that. Would respect that they wouldn't be entirely welcomed on the surface, that they would be, well, outcast. And whilst some did, I think a lot did not. Or treated it less as a 'Outcast' and more as a 'Incast', someone who was entirely welcome both in the Underdark and on the Surface.
The argument, 'Oh but the thing I was outcast for didn't happen on Arelith, so why do people know?' Is a bit like saying, 'Oh but my Undead are -nice- undead! They chose to be this so I'm a nice person!' or 'Oh but I was forced into a pact with a Demon! Forced! So why are you being bad to me?' or 'Oh but my Fey pact is with NICE fey!' or 'Oh my Paladin is actually a Grey Guard, so he doesn't need to be lawful good.' or 'Oh but my Slave is super powerful so he doesn't need to do what anyone tells him to do.' Or any other number of 'I want to have my cake and eat it too.'
If your characters 'outcastness' is such that he or she is fine on Arelith, and entirely unknown... then that's not a problem! Roll up a surfacer. Sorted.
“It is gamifying the game further, and if we continue down this path we will soon be playing Alliance vs Horde since we all know what faction people belong to from right click examine and not from actually interacting with that character.
I see where this comes from. On the other hand, if you want to play an evil character who's presence can't be detected...
Don't make an outcast.
Sorted
The argument that it's a little weird how people are now 'marked' as Outcasts – how it's odd that people are suddenly able to spot them, when they couldn't before – All those points about how strange it is that you can meet someone in the middle of the desert, and suddenly 'know' that they are an outcast just because they're a member of another settlement?
These are actually very valid points. And I do sympathise. It is a little weird. And maybe some day in the future the team will come up with a different, more immersive way of allowing outcast recognition.
The issue however is that without such a marking, one of the key parts of what the background was meant to be (Outcast, clue is once more in the name) was difficult to mechanically enforce and show.
This seems to be at least the easiest way of doing things and also maybe the least mechanically impacting. It perhaps wasn't fair, from a DMs perspective, that we were expecting surface settlments to show the correct amount of distrust for outcast characters when, in fairness, there was simply little way of surface characters even knowing who was an outcast. Or to expect outcast characters to actually roleplay their situation, without some mechanical aid. Is this the most eloquent and reasonble? No, probably not. But it's what we have now.
As for how to roleplay the Outcast Tag? My suggestion (and it is only a suggestion) is to presume it's a bit like a vauge but bad rumour you heard around town.
'Oye, that girl? That one with the blond hair? Yeah... she's -wierd-. I dunno what she did, but they say she got kicked out of her old town. Did something terrible. I dunno what.'
Rumours from the npcs whispered about basicaly. A shifty look about someone.
Maybe you can approach someone with 'Hrn. I think I heard Reginii muttering something about you as you went past. What's your story friend?'
Or maybe outcast players could add something in their descriptions.
There's a few options to make something of this, to actually play the concept of -Outcast-.
This too shall pass.
(I now have a DM Discord (I hope) It's DM GrumpyCat#7185 but please keep in mind I'm very busy IRL so I can't promise how quick I'll get back to you.)