A long time ago, when folks traveled by train, newfangled football stadiums were constructed with seemless seating all around. Folks observed that they resembled bowls. One such construction actually took "Bowl" as part of its name.
Well, the fine folk of Southern California wanted to promote their area as a great place to visit and live. They had the idea of hosting an invitational game between top college teams in their newfangled stadium. They would hold it on the winter celebration of the new year to emphasize their fine weather. Thus, the first "Bowl Game" was born - the Rose Bowl.
Other folks in other parts saw the Rose Bowl as a successful promotion and decided to join in. They would celebrate the uniqueness of their area with an invitational college football game. They would "borrow" the Bowl moniker, whether their stadium was bowl shaped or not.
Well, you see where this has gotten us today. Even if an area has little to celebrate, the locals are hosting a Bowl game.