It's considered unsporting and is a poaching technique. Yes, some game animals will stare into a light not understanding the threat, but the real reason spotlights are effective is eyeshine; the light reflected from the eyes of game animals makes them easy to find at night.
There are many effective techniques that are not permitted when hunting game.
Oh I see. I just didn't realize that that was codified into law so that police would stop you from doing that. Would have figured it had more than just unsporting as a reason.
Here is a current publication[1] that covers the rules that apply in a typical Midwest state. Page 19 covers use of artificial lights and various exceptions. There is a great deal to know and conservation officers enforce these rules enthusiastically.
Incidentally, the use of radios is unsporting in Kansas, and therefore forbidden (unless you’re hunting coyotes—they’re considered a pest, so you can pretty much do whatever you want).