When playing solo, items are not an issue, since everything is kept to yourself. However, when playing multiplayer, either with friends or randoms, loot is on a first-come first-serve basis, and as such it feels like knowing which items to pick up and which items to leave for your teammates would come in handy in making bossfights and tougher enemies easier to handle.
After recently unlocking Engineer, I've started to understand the meme about Bustling Fungus and him, like in this image:
That said, it'd be nice to know what items the other classes most benefit from so the team can be the most optimal. There are so many items in game that it's hard for me to figure out which exactly works out.