Well overgeeked, it's like this. If there's no place in your game for that "fantasy", that's fine.
That's not what I said. It shouldn't go unexamined. Some nobles will certainly welcome you, say the allies of your house or clan or whatever. But those opposed to your house or enemies of your house? Clearly not...yet the ribbon feature doesn't take that into account...nor do most players. Same goes for how peasants interact with "noble" characters. Not every peasant is going to be a boot-licking toady. Some will utterly hate you simply for being a noble. Depending on the town and the peasant, "I'm a noble" is more likely to get you murdered than helped. I get the fantasy and I have issues with it, but the way the background is written is way more problematic.
I didn't really expect to be treated like a king when I chose noble for my character...
I mean, that's literally what the background says, as I quoted above. Peasants will fawn over you and other nobles will welcome you in. If the feature works as written, everyone treats you like a king.
but I did think it would be more useful than it ended up being.
Yeah, that always sucks. Differences in expectations between the players and the DM.
I mean, even in AL, I would occasionally see an adventure that says "hey if a character belongs to this Faction or has this Background, this happens". I just never got my turn at bat, as it were.
Yeah, that's lame. I can't speak to AL as I don't play that.
Obviously, as Maxperson has pointed out, this is campaign-dependent; if a DM wants to work Backgrounds into their campaigns, great, since I think the intent is that they do- but without guidance, a player can pick a Background that doesn't really matter in the game that's being played.
Absolutely. That's a feature, not a bug. You can have any kind of background you want, but it won't always matter to the game. That's just part of the game. Your class won't always be front and center. Your skills won't always be front and center. Your spell choices won't always matter. Etc.
Like if I'm an Outlander or Outlaw and we're working for the rightful ruler of a land, that might be a disadvantage! Yet the Background implies that being an Outlander or Outlaw is an advantage.
Exactly. Context matters. But the 5E design philosophy is more and more zero disadvantages and only advantages. To the point of absurdity. Even from the start. Like noble. No downsides, only upsides.
A lot of space in the PHB is devoted to Backgrounds, so I don't think they were intended to be vestigial, yet they certainly can be,
Well, 16 pages out of about 320. Whether that's "a lot" or not is up for debate.
and you do get DM's who say "you have no right or expectation for your Background to matter".
Well, yeah. It's their game to run. If your background doesn't matter, it doesn't matter. Just because you picked noble doesn't mean the game should change so that noble is now important if it wasn't before.
Who could blame a designer for realizing they could have bypassed this by giving each Background a mechanical benefit instead of a vaguely defined Feature?
Um...literally anyone who's played an RPG. Either it's specifically defined or it gets lost in interpretation. WotC learned that in 3X, codified it in 4E, and threw it out with 5E. They intentionally designed it to be vague. That was a choice they made. The ethos of 5E was a return to DM rulings not rules. That's one of the main pushes for 5E. So again, that vagueness is meant as a feature, not a bug.