The {} syntax is better, and more similar to f-strings. And you don't have to use that backtrace. I use it to send json for some batch jobs, or have it write to google cloud logger for gcp jobs. Are you holding it wrong?
For gcp jobs you can just output the structured log in the standard output so I don't see the purpose here. There are other structured logging libraries if this is what you need.
For the backtrace yes, because logging.exception will be broken by default and all tools that process the backtrace automatically like sentry. And again, for no valid reason except than "look, my traceback looks so much cooler on my screen because I added crap and new lines when printing it"...