The key is the voice control. Trying to do it via an app, a remote, or even remembering the switch UI isoften too heavy-weight. Being able to say just "Alexa, living room 50%" is very nice. Same thing with being able to turn off my bedroom ceiling lights without getting out of bed. Sure, is it required? No. Can I get up? Sure. Was it worth $50 for the smart switch? For me, yes.
Turning off the lights is negligible to your overall health. Automating it (or not) will not affect your obesity or other health outcomes. There are lots of reasonable arguments against IoT switches; this is not one of them. Let's move on.