A simple, yet vital part of any gym, home gym, or workout area are weight benches. Benches provide you so many more workout options with dumbbells, bar weights, and body weight exercises that you otherwise would never be able to do standing up or on the floor. Weight lifting benches may seem insignificant, but if you don't have one, you don't know what you're missing and if you do have one, it would be very difficult to go without it if it were to vanish. Workout benches also provide you with stability and form control that keeps your back straight, your feet flat and an even (and cushioned) surface on which to get your exercises done.
Some benches can incline and decline while others are simple flat benches. Both of these options are useful and obviously incline/decline benches provide you with more versatility, but the simple fact is that a home gym is incomplete without a bench.