Need varies for each individual and particular circumstances.
Lets be happy that we all have the right to define need for ourselves, and support one another's right to define that need.
No two individuals may always hunt in exactly the same manner, the same environment, for the same animal, with the same rifle, cartridge and ammunition (whether it be factory loaded or handloaded). This is the reason why there is choice, and I for one am happy that we have that choice.
Some are hunters that take pleasure in the thrill and skill of the close range hunting, while others are shooters that take pleasure in the thrill and skill of long range shooting. Just because I am not a fan of long range hunting, does not mean that I should bash those that do. I admire those that take the time and effort to purchase the firearms and practice with them to acquire the skills needed to perform long range shooting. )I practice shooting at 400 and 500 yards, where the range allows for this, as I know that I must be prepared to make a long shot on wounded game in the event that things do not go as planned. It is our responsibility to make every effort to follow up and cleanly finish and bring that game home.) Just as I admire those that take the time and effort to practice the skills to hunt their chosen target animals at close range, as they must learn more about the animals and their environment, and pay more attention to how they move and what the wind is doing.
For me, I own both standard and magnum cartridge firearms. And I enjoy both; in both the shooting and hunting with these firearms and cartridges. And I am glad to have the right to choose to own and use both! And will not apologize to any for having both.
I will say that I own far more non-magnum cartridges, and as I get older (and hopefully wiser! LOL), I enjoy the ability to practice more due to reduced recoil. A large part of this has to do with the fact that many of these firearms are lever actions that are not offered in magnum calibers, and are user-friendly for us left handed shooters. Not to mention the nostalgia factor passed own from parents and grandparents, and western movies and novels enjoyed over a lifetime!
Until I found and acquired larger calibers in non-magnum cartridges in left handed rifles suitable for the larger big game animals such as moose, elk, grizzly and bison, such as the 338-06, 376 Steyr, and 9.3x62, I bought and used magnum cartridges in rifles to accomplish these tasks, such as the 270 Wby Mag, 7mm Rem Mag, 7MM STW, 300 Win Mag and WSM and 338 Win Mag. And they worked just fine. Could I have accomplished this with the 30-06; Yes. But as I am not a big fan of the grand old '06, I wanted to own and hunt with something else, and did so, with no reservations, shame or apology.
I own a 416 Taylor, and while it may not have magnum in its title, it is based on the 458 Win Mag case. Do I need it; No. But wanting one to shoot, and hunt bison, and grizzly bear, and if I ever get the chance, brown bear or cape buffalo, I look forward to hunting with it!
And yes, now that I finally own a lh 9.3x62, it probably not needed...buy I wanted one and enjoy owning and shooting it!
While I may not have owned a 416 Rigby, and I probably never will in a left handed rifle, I chose the Taylor because I could find properly headstamped brass, and it fit handily in a left handed long action with magnum bolt face.
Lets all continue to enjoy our right to choose, and support those that also have this right, even if their choice is not the same as ours!