There was a time when CTL-ALT-DEL carried some authority on a PC and could be used to force a shutdown. Now I find it is usually completely ignored. On the devices which lock-up and won't shutdown (or restart), I guess we've all had the experience of having to remove the battery to turn them off. For devices without removable batteries, we just have to sit the device down until it runs itself dead.
When Apple released first iPod touch, they eliminated almost all mechanical switches. It even didn't have volume up/down button. Great, until you carry the iPod and get into subway station. Every time you get on and off the train, you have to bring up iPod from your pocket, unlock the screen, open control panel and change the volume "by touch". It was terrible design mistake. Fortunately Apple was not a fool - they added mechanical volume buttons on subsequent iPod Touch and iPhone.
But I still don't like iPhone's "unlock by slide" feature. I wonder whey they didn't put a nice, mechanical, positive-feeling, one-hand-operational unlock switch, just like not-so-frequently-used "silent mode" switch.