Uh, I agree that an extra effort to make the custom-made character as interesting as the origin characters, both in SP but also in MP.
In the character creation it´s showed that Origin characters have the standard backgrounds too. Lae´zel is a soldier, Gale is a sage, etc.So I do not think the background would be something that could make a meaningful difference between origin and custom characters.
I think backgrounds itself will work the same as tags in dos and Iwd dialogues. The NPC will react differently if your character has a background or feature.
That said, those things you mentioned about backgrounds are just guidelines (blackmailer, etc) ,they´re not mandatory . Most players usually write their own story but if they don´t or they do not feel inspired, the manual will give you some optional guidelines, the ones you mention.
You can also roll a random character: You roll a d10 and take the defining event with that number for your character. Same with a d8 for personality and d6 for ideal and flaw.
And then you write a characters based on those options if you like improv.
The thing that all backgrounds give and it´s the same for every character are the skill/language/tool proficiency of that background and the feature: criminal contract for criminal and "Rustic Hospitality" for folk hero; but his/her story is made by you.
Every character has to have a background, but they can have backgrounds be more meaningful for custom characters, while still just letting backgrounds simply provide tool and skill proficiency for Origin characters. All the custom characters hail from Baldur's Gate, The Underdark, or the Astral Plane, so letting backgrounds influence how the people of those places feel about a custom character can go a long way in making them feel meaningful, which is what I tried to explain in my post. Skill proficiencies, and ability score is a nice step towards making custom characters more meaningful, but they can go further with it using the player's handbook's suggestions as a part of character creation.
