Re: Irrational
The slower might rather be an advantage when it comes to the use case for the Harriers (or the V/STOL F-35), close air support. There, slow is better, as it helps to deliver it payload closer to friendly troops with better accuracy.
The same reason why it will be a sad day for the US military (and a lot of friendly nations on the same missions) if the US Airforce is ever to retired the A-10. The jet-jockey brass all want to play Ricky Bobby and go fast, but that ain't helping the guys on the ground...