They can be handy but not always. On some forest service roads, low-hanging trees can give taller vehicles a disadvantage and they don't exactly have the budget to go around trimming right now. And getting stuff up and down from there can be a pain. But IMO it's better than truck tents. (I know they have their fans but I'm not one of them.

I hate having to pack up camp and potentially lose my spot just to run into town or a few miles down the road to glass another area.)
I don't run a rack like that, but I do use cargo carriers. I added a front receiver to my RAM and love it. I have a winch on a mounting plate that I can throw on if I really need it, but 95% of the time (like probably everybody that has a winch) I never use it, so I can put a cargo carrier on there. That holds one of my two coolers plus a small bin with my truck chains and a few tools. I could easily carry more but I like to keep the front load low so it doesn't obstruct my radiator (much).
On my rear hitch I have another cargo carrier with a second cooler, small generator, gas can, etc. It looks a little unwieldy but bear in mind with the coolers empty there's no weight to them and when full they balance out so it rides very well and this leaves my entire cab and truck bed free for other things. I only have a 6.5' bed and have never felt like I didn't have room for "honestly that's way more gear than I really need..." And despite the added length I've never had a problem getting down a FS road...
I guess it depends what gear you want to bring. Most of those racks seem to be either cheap clones best used for carrying light things like ladders or custom jobs with tons of attachment mounts that I call the "chandolier-o'gear" - axes, shovels, traction boards, water and fuel carriers, etc etc. I'm kind of hard pressed to think what hunting gear I might want up there - coolers are so bulky they'd really hurt your fuel mileage, I wouldn't want my backpack up there pounded by 80mph wind and road grime, food would get ruined getting baked in the sun, etc. But YMMV.