I think gold you earn on kills should start low and go up over time.
1-5min =100gold 5-10=150g 10-15=200g 15-20=250g 20-25+=300g
laning phase you all ready lose a lot of creep score =less gold and xp. So the loss of gold and xp from dieing is all ready huge. So i think scaling the gold over time will make it so games are not so 1 sided due to a couple mistakes early in game.