The phrase "why not restaurant" appears to relate mainly to the name of several restaurants called "Why Not," which are known for offering unique dining experiences. For instance, "Why Not" restaurants can be found in various locations such as Gent, Nijmegen, and Epernay, each providing a distinct culinary style and atmosphere.

• "Why Not" in Gent is a gastrobar known for exquisite dishes and artisanal cocktails in a cozy setting.
• "Why Not" in Nijmegen offers a dining experience centered around a Josper Grill, a Spanish charcoal oven, providing Mediterranean-style grilled dishes.
• "Why Not Restaurant" in Epernay is noted for excellent French and European cuisine with a good reputation among travelers.

Therefore, "why not restaurant" often refers to a restaurant brand or name associated with innovative, quality dining experiences rather than a phrase questioning why not to go to a restaurant. If the question aims to explore reasons for not going to a restaurant, the search results do not directly address that. It instead provides information about places named Why Not Restaurant or WhyNot gastrobar establishments. If more specifics on reasons not to go to a restaurant or a particular aspect are desired, please clarify for a more tailored answer. These findings relate primarily to the concept of "Why Not" as a restaurant name and brand in different cities rather than reasons against restaurants themselves.