If the switch itself illuminates so that it can be seen in the dark, then you will need power to the switch...also, if the switch is variable such as a dimmer instead of toggle, then power is required full time.
12VDC inside a house is something that I have not seen, but have seen that used to operate landscaping lighting. If it works, why not keep it...tho if replacement parts are not available then it's time to think about upgrades.
The only time I have dealt with power at the light was when a pull-string switch was used for an Edison base in a closet or small room or the entrance to attic space. I ran lights in my attic operated from a toggle at the entrance to replace the single Edison base bulb light, as I had leftover materials from another project and converted some of the attic into storage.
I spent a LOT of time in blown insulation attics, and the only thing that helped was to wear a woodworking mask to keep from inhaling the irritating dust. When I didn't and was moving around too much up there, I regretted it for hours afterwards. I definitely had to hit the showers afterwards as I would be covered in itchies.