ext4 is still solid for most use cases (I also use it). It's not innovative, and possibly not as performant as the newer file systems, but if you're okay with that there's nothing wrong with using it. I intend to look into xfs and btrfs the next time I spin up a new drive or a new machine, but there's no hurry (and I may not switch even then).

There's an unfortunate tendency for people who like to have the newest and greatest software to assume that the old code their new-shiny is supposed to replace is broken. That's seldom actually the case: if the old software has been performing correctly all this time, it's usually still good for its original use case and within the scope of its original limitations and environment. It only becomes truly broken when the appropriate environment can't be easily reproduced or one of the limitations becomes a significant security hole.

That doesn't mean that shiny new software with new features is bad, or that there isn't some old software that has never quite performed properly, just that if it ain't broke, it's okay to set a conservative upgrade schedule.