I say leave it as it is. Using only one set of brackets isn't even what I'd call 'bad' coding, as it's still very clear what you're trying to do.
That's why I put quotes around "badly". I think leaving it as-is would be fine. Making it less strict would be bad. Making it more strict wouldn't necessarily be bad, but would break enough scripts that I doubt it would happen. Besides, the current method has worked perfectly fine for a long time, so there really isn't a reason to change it, so I agree with you.