That works of course. My hand-held 2m handy-talkie has a switch on its volume control knob that turns It off when twisted fully counter-clockwise. Many audio devices implement the same functionality, wherein it is desirable to turn on the audio without blasting you out of the room, which could happen if the volume control and the on/off switch were separate.
Wait! My living room Samsung HDTV does exactly that because it drives a multi-function receiver that is "on" all the time. Gotta be careful to mute the receiver before turning the TV on!
Talk about clutter though: there is an IR remote for the Samsung (used to select a TV channel), another IR remote for the receiver (used to adjust audio volume), a Bluetooth remote for the Sony PS3 (used for all sorts of things), and now (thanks to Time Warner Cable) still another IR remote to control TV channel selections when TWC goes "all digital" in the near future, apparently eliminating all the cable RF channels the Samsung routinely tunes (including high definition), or at least the un-encrypted channels. Soon all the channels will be encrypted and require the Cisco TV Adapter and its IR remote for each television in the house. We currently have four set-top TVA boxes, none activated or connected yet.
I still need TWC to provide broadband Internet connectivity, but I may put up an outside antenna for free OTA high-definition TV. We already stream movies using Netflix and Amazon Prime, so I don't "need" the dubious privilege of "tuning in" whatever programming TWC sees fit to allow down their pipe for "Starter TV" service.
Yeah, a PSU can be cluttered, especially if you have DPMs to measure voltage and current, voltage adjust and current adjust controls, power switches to enable or disable outputs, 5-way binding posts if its a bench PSU... yada, yada, yada. I would prefer a "glass cockpit" approach with a backlit, touch-sensitive screen that displays and controls everything.
Maybe an iPad tablet would make a good PSU control panel, although it pains me to think of putting out that much money and wasting that much processing moxie just to have a classy PSU front panel. I happen to have a small touch-sensitive LCD panel that interfaces to Arduino, but I am thinking something with maybe eight or ten times more area would be better if someone would sell it for, say, twenty bux. Then all I would have for "clutter" is the 5-way binding posts.
Good luck finding the potentiometer and switch combination you want.