Graves was actually intended as a bot lane marksman if I remember correctly. It just turned out that he is better in the jungle.
The body blockable auto attacks give Graves a hard time trading and farming in lane. But since he worked out in the jungle, they just embraced it instead of shifting him to bot lane (which would be pretty hard to balance correctly).
Talon was never intended as a jungler. And unlike Graves, his ganks would be alot more powerful. Graves can't go over literally every wall in the game with his E, Talon is able to. On top he has the invis on his ult.
As a mid laner, Talon can still use this tools to gank other lanes efficiently. The difference is that this time the other laners can get warned,since their mid laner can just ping them that he is missing. If he is playing the jungle, this warning isn't possible. He could jump over the next wall every time.
Camille and Kled got restrictions for that same reasons, too.
Kled doesn't gain courage from killing jungle creeps, while Camilles W didn't heal on creeps (doesn't heal on minions anymore either, though). Their ganks would be pretty powerful if their jungle clear would be allowed to be healthy.