It makes a lot of sense when you realize that they need to capture the sound of contestants and they are also moving around a lot. There’s no way to use fixed mics all the time. Obviously not everyone is provided with a wearable microphone.
And the shorter the microphone is, the more the host has to exert himself by holding his arm up near contestant faces.
A long lightweight microphone is the perfect solution.
Well, Let’s Make a Deal outfits are sillier, but, at least when I used to watch The Price is Right, which was admittedly many decades ago, audience members often wore loud colors and silly shirts and that sort of thing.
Looking at some more recent pictures, it looks like it’s still pretty common for audience members to wear custom printed t-shirts with silly things on them. It’s certainly not as silly as it used to be, though.