Like you, I also deal with the kinda weird uwsgi logs. I feel like "universal format" probably didn't mean the format of all the lines in all the logs is the same - though your definition is probably more accurate.
Despite that, I can be pretty sure when I walk in to a foreign system there will be nginx logs, just where I expect them, almost certainly in the format I'm used to. And even if the format differs, it's not much of a problem. Binary logs, big problem.
Sure, on a site that uses ElasticSearch for its logs I would have no idea where to look at. I'd be more at ease with SQL, but first you need to locate the DB, figure out the schema, get the SQL dialect right.
That said, I'd be far more at ease writing a SQL query to extract analytics from logs than cooking up some regexes and doing complex stuff with awk.
And I find the --since/--until parameters to journalctl far easier than matching dates by regex. Or even the --boot parameter to restrict logs to a specific boot, which with would be probably doable with awk but definitely not as trivial.
I think that binary logs give you some compelling features, without taking away any: you can always just dump the logs on stdout and use grep as much as you want. :)
Despite that, I can be pretty sure when I walk in to a foreign system there will be nginx logs, just where I expect them, almost certainly in the format I'm used to. And even if the format differs, it's not much of a problem. Binary logs, big problem.