In their world, resisting surveillance will be probable cause for arrest, because you must have something to hide and need to be investigated.

One of the biggest criticisms of English is how reading a word doesn’t teach one how it is pronounced. So it’s not redundant since it addresses an actual problem.

It was indeed superseded but that doesn’t mean it disappearing was good. Limitations of printing were involved.

It is annoying to read because you’re not used to it. Were you used to it, you’d think “th” annoying. By your logic, everything you’re not already used to is automatically bad.

It being hard to type was a question from OP.

Not everyone does it, and it’s ahistorical, but I think it’d a cool way to distinguish between voiced (ð) and unvoiced (þ) dental fricatives. Why not have two different symbols for these? Eg: ðe þin faðer þinks about ðis (the thin father thinks about this).

It’s not necessarily hard to type, on my computer it just happens to be AltGr+d (ð) and AltGr+t (þ).