1st question is.... Do I need a portable torch? Do I keep using the light on my phone to look at stuff and does it do the job?
Now, me personally, I have a handful of small 1 watt torches dotted around d the house and 2 work lights (1 picket version and a larger brighter version).
I have had a couple of powerbrick with built-in torches, but never used them. However, if I was still working as a plumber (or a sparky) I'd find it very useful and would pay a few bucks extra for that feature. As having a reliable rechargeable small torch that's quite bright, was really useful as a plumbers mate.
The torch would need to be a 2 watt light at least to be of any real use. A nice cuboidic powerbrick with a bright light is obvs more stable than a round torch.
I also have a bright 1w keyring torch, and I've carried one for years n years. Originally it was because in winter a couple mates doorways were easier to find if you had a torch and I found the original mag-lite solitaire useless, but now we have LED which makes things so.much better.
So on the 2 questions,
1, it's not technically a missing feature, but could be an option.
2, I think a someone who works in darker places or needs an independent light source, say under the kitchen unit or under the stairs etc etc, then yes, you want a torch. I think to make.maximum use of such a feature, it would need to be a decent sized powerbrick and a decent led (the new COB bulbs, are fantastic brightness to.oower usage about at the mo). But a led that doesn't suck all your juice in 30 mins use. Otherwise you'd look at professional torches that use a drill battery (such as dewalt, ryobi, metika) but they won't charge your tablet/phone.