I personally liken the big belted cases to the cases on the other end of the scale, the small caliber cases ie. the 17 Remington and 204 Ruger and their like.
They fill a very specific niche. In the sub calibers it's shoot a fast little bullet with zero recoil in a centerfire rifle and not blow up coyotes etc.
They aren't better varmint rifles for generalized varminting, that falls to the 223 or the 22-250 predicated on what and where you hunt.
Same deal with the big belted magnums. Do you need one, no. Does brass or ammo cost more, yes. Will the non belted, non magnum case do everything that a bigger belted mag will do, no, not unless that case has the same case capacity.
The belted mags, most of which are over bore, work best with the heaviest bullets for caliber. That's where they shine. If I know the shots might be long and I'm hunting elk, I use a 338 Win Mag. Deer or stuff smaller than elk a 7mm STW.
All the rest of it, brass life, barrel life, reloading ease etc. is a smoke screen. Very very few guys arre ever going to shoot a belted mag enough to wear out the barrel. Buy a hundred cases and shoot you rear end off and hunt a lot. If you really try most guys MIGHT shoot 500 rounds of ammo this size, in a life time.
Just buy and shoot what you want, it'll be just fine.