If it was risk free - like upgrading software (though even then, a software upgrade can break other software), it wouldn't be an issue.
But a failed flash (eg. power failed at a critical point), can render a drive unrecoverable (although 3rd party tools can sometimes force a recovery).
Also, withough unofficial tools and/or an available or saved copy of previous firmware, it can often be impossible to go back if the updated firmware didn't work as expected.
If you foul up with software, you can always bite the bullet and format/reinstall the entire system - that last ditch option is not available with firmware - neither can it be backed out by tools such as GoBack.
In the case of Liteon, practically every update is marked as "Match more media" - with many other makes, it's rare to get ANY description for a firmware update.
Now there was a point, when older drives NEEDED an update, as there was a potential problem with newer media (sounded like the laser calibration could exceed the allowable limits for the laser).