I mean this with all the love in my heart: you are naive if you think modulating the rewards will in any way stop AFKers and botters as long as the risks are so minor. As long as there's any reward whatsoever, people will do it. Removing all rewards from last place won't stop that, either, because there'll still be a trickle of a chance that they land in second or better. They aren't 'wasting their time' because it's not their time to begin with - the point isn't to be most efficient, it's to get something for nothing.

Until real change is implemented with regards to kick timers and punishment structures, they're not going to go anywhere. Changing the reward structure is just window dressing that doesn't solve the major problems and instead makes it a less attractive option to active players.