Alright, you don't want to wait 5 seconds, but if you kill someone while going to the wool, would you like that the same player you killed, kill you after 2 seconds of being killed? I think that's a pain as you may killed him but he also damaged you, so he will respawn with the whole life and he also has more chances to kill you because of the before taken damage.
But in the killed point of view, it's also a pain that you were trying to kill someone that was going to the wool but he kills you, and then you will have to wait 3 seconds until respawning and try to kill him again. Yes, I know it is a pain, but you also have to understand that if he kills you, at least give him more time to have a little chance to get that wool and you for sure are not the only one who will try to kill him, so I think that's fair for both of the players.
Conclusion: Not having a delay between spawnings, it's to cheap for the killed one, but a pain for the killer, but the killed will also have to kill few more players between you, so it's fair enough.
That't my opinion, if you have something to add, or something to argue, reply by quoting me and refering to each thing.