[acdha]

That's because your text editor has had thousands of hours of work going into catching all of the edge cases.

Things which have caused editors to hang or crash: 1. Binary data outside of the US-ASCII visible range 2. Malformed or creative Unicode combinations 3. Very long lines 4. Very many lines 5. Inconsistent line termination 6. Lines with patterns which trigger syntax highlighting, URL underlining, etc. 7. Embedded terminal escape sequences

It's not unreasonable to imagine that the journald developers might spend the same amount of time on safeguards, something which is easier with a well-defined binary format.

[CameronNemo]

Yeah so let's just redo all those thousands of hours of work... for one specific format that has literally one use.

[acdha]

It's not thousands of hours with a better-defined format than free-form text, which is obviously the case for journald. Doing that for a single format makes sense for something which would be as heavily used as system logs – it's not like people haven't spend crazy amounts of time writing syslog parsers or other hassles which go away with a structured format.