Lighter, you are right, but older origins do not constitute any claim to "correctness". Logic can be a slightly stronger argument, but not sufficient either. Formal language and pronunciation is a mere convention, for England typically defined by the BBC. We agree that speakers and writers are not required and sometimes not well-advised to stick to it, but if they want to, they had best do it properly.

An example where logic disagrees with all levels of English language: "I don't think X" is often and "correctly" used when the logical meaning is "I think not-X". It may be a case of "fossilized" ironic understatement, much rarer in other languages, or even considered an anglicism there.