RO isn't BF2, it isn't DoD, and it isn't CoD (1 or 2) either...
Put in the throw option. Please.
The idiots may choose to run to a nade & try a throw, but they'll learn not to.
The experienced players may choose to avoid grenades or throw only if it lands on them.
BUT, at least the choice will be there. Right now you have little or no choice. If you're in a room when a grenade is popped through the exit, you're buggered - by grenade, by bullet, by bayonet, you're just buggered. If you could throw the grenade back - even IF you may die - you'd try it - just to save yourself.
That's IF it was implented in the game. So I sure as hell hope it is.