When you’re holding a plastic camera it feels more like playing with a toy than a serious instrument of photography. Probably because it is a toy camera. But shooting with one can lighten the mood and open up new inspirations. The pressure is off. I don’t feel like every frame *has* to count, and sometimes that can lead to taking chances you might not otherwise take.
Another plus (sometimes) is that the results from these toy cameras can be rather unpredictable. Plastic camera bodies are prone to light leaks, and a lot of them have irregular lenses and a fixed aperture. Throw in a roll of expired or color-shifting film, and all bets are off.