Structured logging is the practice of logging in a structured, parsable format as opposed to an string with no well-defined structure. This is great because it makes it easier to filter and search the logs for relevant information, improving the Observability.
There are several formats to log, but people mostly use JSON or logfmt. I tend to favor logfmt as it is easier for humans to read and as easy to parse as JSON.
Tools such as Logstash and Loki allow us to parse, filter and visualize structured logs.
I see no reason to not use structured logging instead of traditional logging in an application.