Yeah that sucks. But that said, I don't think I've ever seen a major software/firmware update on any device that doesn't warn you to backup your data first. I've said this time and time again, have a regular backup routine! This also extends to your phone. In fact, if you're reading this, take a few minutes to connect your handset to your computer and copy your important photos and stuff over, so many people don't do this!
As for this error 53, well, I'll put that down to half-baked Apple engineering and software development. If indeed this error is due to some "hardware fault" which the new firmware detects, wouldn't it make more sense to do the scan before the update and give the user some information that "bla isn't working, go see your Apple dealer or continue at your own risk"?
I know when I've updated Android and BlackBerry handsets in the past, they go through all sorts of checks and balances before the update will even kick off. And even then if you brick it, it's not hard to revert to a previous ROM version or if it fails half-way, it will automatically roll back.