Regular is actually incredibly useful because it allows you to confidently parse or validate (large amounts of) untrusted data without having to worry about DoS

Regular is actually incredibly useful because it allows you to confidently parse or validate (large amounts of) untrusted data without having to worry about DoS attacks. I'd argue that this is useful, even if you use it as part of a parser that doesn't just parse regular languages, as you'll have a slightly easier time reasoning about the time and space complexity of the construction.