I see this argument all the time and sometimes get wrapped up in it myself. From the sounds of your collection, you certainly don't need it but so what? The better questions would be, "Do I want one?" and "Can I afford one?"
I had a Remington 700 ADL in 30-06 with a decent 3-9x40 scope. With all the different ammo available, and the fact that I reload, I can shoot everything from varmints to Kodiak and never feel like I don't have the right gun.
But I'm not just a hunter, I'm a "gun guy". I like to own them, shoot them and trade them. I have a 7mm-08 Rem. 700 Mountain Rifle and I absolutely love it. With the tiny barrel contour, it struggles to shoot 2MOA with factory ammo and a .75" 3-shot group is the best I've ever done with my best hand-loads. It's light, has great looking lines and does a great job on deer under 300 yds. By far, it's the rifle I reach for most often.
So why did I just trade the 30-06 and get a both a heavy-barreled .308 and a Sendero in .270? There isn't a nickel's worth of difference between any of them! The answer is that I had the money and I wanted them. What more justification do I need?