Ten years ago or more, I would have urged anybody to learn to drive in a manual, unless they really couldn't manage it owing to disability, extreme anxiety or whatever - as it just opens up so many more options to you.
Imagine being in a situation - borrowing a friend's car, courtesy car, hiring a van etc. - where you're there with a driving licence and a vehicle available to drive, but because you never learned the tiny fraction of driving that is clutch control and changing gears, you're in no better position than if you'd never learned to drive in the first place.
However, now, I don't think I'd be so hardline about it. My DS is 10 and, by the time he starts learning to drive, the vast majority of cars will be electric and thus auto. Indeed, it will only be a matter of time before driverless cars are a common option, maybe the norm; in fact, we may get to a stage where it's actually made illegal to drive a vehicle yourself. Think about various items of machinery now that come with in-built safety features, and you're banned from/strongly advised never to use them without those safety features. I can see a time when allowing a fallible 'meat bag' to override the automatic 'safe driverless mode' by wanting any control of a vehicle is considered gross misconduct - and maybe even opening you up to prosecution!