Does it bother you that the wizard in the party knows more about religion than your cleric? Or that the forester/outlander barbarian knows so little about nature and survival, even though he can easily find hidden sources of water in the hot savanna after being raised in snowy mountains in the neverending cold of the frozen North?
Do you think Acolyte and Outlander are boring backgrounds? Would you prefer to be a Former Cultist of the Great Old Ones or a Savage Barbarian of the Icy Peaks?
Do traditional backgrounds leave you cold? Do you prefer your characters to be special snowflakes? Are you reading this after all these puns?
If the answer is yes for any of those questions, try this.
|A samurai background is easier to do than a samurai class (art: copyright WotC)|
This is not new, of course; compare the Uthgardt tribe member from Sword Coast Adventurer's Guide with the PHB's Outlander and you'll see what I'm talking about.
Also, since the PHB doesn't mention it explicitly, let me suggest that you use these backgrounds as sources of advantage. For example, let the Acolyte of the GOO (or Sorcerer, for that matter) get advantage not only in his religion rolls, but also when trying to intimidate the superstitious. Give the Outlander advantage when persuading other tribes that share a similar culture. And so on. Don't get too crazy, though: them sorcerer does NOT get advantage in all her intimidation rolls because he can cast a cantrip.
By the way, that is also how backgrounds work in my Days of the Damned game, as I mentioned it in this post about 13th Age. Click the link for other examples and a discussion of some pitfalls this technique may cause.
Want a downside to go with it? Your background feature also become specific, if it isn't already. So the GM may rule that your Outlander character must roll the dice to find food in the savanna. He rolls with advantage, of course, since the feature is still included in the background. If you think this is too harsh, let the Outlander use the feature as written after a few successes in the savanna. Same idea can be applied to a pirate's reputation; let her make some intimation rolls at least until she gets a reputation in her new home.
Many backgrounds are already quite specific, so no need to change those. And, of course, don't make the players roll for stuff that should be obvious! Of course the Acolyte of Cthulhu knows it waits dreaming in R'lyeh!