Your bench will help your press.
Bench press builds chesticles.
Bench allows you to handle more weight.
If you bench properly, using good form, you strengthen your shoulder, not weaken it, which means your less susceptible to injury.
Having more weight pressing down on you creates a greater stimulus to the whole body, but esp to shoulder girdle.
Triceps strength.
Keep sport options open (i.e. powerlifting)
Bench is full body. Re-read Rips chapter on benching in SS if your unsure why/how AND google Dave Tate's how to bench video.
Bench balances physique and development.
Greater bench strength = more pushups/faster pushups. Improving your bench will improve your pushups faster and safer than weighted pushups.
Explosive punches.
Heavy weight pressing into forearm fosters better overall development of forearms than just pulling does.
Chicks dig it.
Guys will respect you more if you have a decent bench, and this gives you a psychological edge in some situations.
If you fall of your motorcycle and stick out your arms, they and your shoulders will be better able to absorb/defelct the blow from landing.
That's all I can think of and more than enough. Just bench.