> As a simple solution, one could pass a signed auth-hash of the fields generated by form_for, and the server could re-hash the fields submitted to ensure the form data you asked for is what you get (this solves the primary issue with attr_accessible).
If you turn it off then you're back to square one security-wise. Apps that have neither APIs nor JS are an increasingly small share these days. Also consider what is possible to sign. In most cases there will be some non-enumerable data in the field, leaving you with only being able to verify the field names, but there could be nested data and it seems like a 50/50 shot that whatever unforeseen vulnerability would not need to change the top-level params anyway. I don't think this would afford much of a security guarantee.
The only way to fix this by "more of a focus on security" would have been not to do clever things with parameters in the first place, but the clever things provide a lot of value, so the next best thing is security auditing and be on top of patching any vulnerabilities.