Ok, situation sketch:
Team A is standing at mid tower to defend. I come in from the side. I throw a diagonal spear through the group. It forces a silly carry (I'm not playing pro leagues, so bear with me) to slightly move west (actually East would be better, different pov, since I wouldn't eat turret fire, but for the example, it will suffice). I immediately follow this up with a spear throw on the carry, use R, W out. The target is slowed, gets picked off as a first target and completely molested. It's now 4v5.
Let's say you are chasing a set of opponents. They're equally fast as you are. You switch to R, W twice, R switch back, AAT (javelin) the back of the first or more important target and pick it off from the group.
I mean, it's not just on melee attacks. It's from basic attacks
My thought process is to keep that spear to install fear. As long as people fear it, they will fear you. As long as they fear you, you become a target, which is something that's incredibly useful when you're called Nidalee and have virtually no way to get caught indefinitely.