Probably the earliest encounter a new player has with Utility slot items is Bret's Hopper Roundup. Taking a bunch of Throwing Nets and Dog Crates out into the field, the player finds they can activate them by right-clicking them. The Throwing Net can be equipped in a Utility slot. Mysteriously, the Dog Crate can't. Instead, the player needs to keep the Inventory window open while chasing Hoppers. This can occupy a significant proportion of the Underrail window at minimum resolution.
If the Dog Crate were flagged as a Utility item, it could go in a slot beside the Throwing Net leading to a much more streamlined experience.