The bonus gold gained through kills is based on the net worth of the enemy team, if they are far ahead of your own team you'll gain a lot more gold. It's the same in DotA 2, known as the "comeback" mechanic. If you are far ahead and make a mistake and die, your enemies can catch up. In the end it makes games a lot more unpredictable (which is a good thing) and less snowball-y.
Mistakes are punished much more severely. I like it, coupled with the buff to buyback (from -100% gold bounty from creepkills to -60% bounty), it's way better than just punishing dying by increasing buyback gold and or higher death times.
If it's changed in DotA 2 somewhere in the future, we'll change it in LoD too, but for the time being 99% of item changes and various gameplay changes (such as this gold bounty one) from DotA 2 are ported 1:1 into LoD.
There is a reason so many of us quit vulva doto and went back to wc3. This is one of the biggest.
It does not enable enemies to catch up. It makes/forces them to catch up. It does not make games a lot more unpredictable, it makes them a bit more unpredictable and a lot less strategic. You do not need to worry about anything besides getting kills, farming, splitpushing, taking out enemy carries/teamfighters does not matter, just nukefest them all for max gold. Picking off a support is not longer a small deal, since anyone gives gold based on their teams networth.
More still, you get punished even harder for feeder teammates. Not only do they feed, but their feed is worth more based on your kills/farm.
You could always make comebacks, it was harder, but it was based on skill, not enforced by the system. And it makes all the targets the same, doesn't matter who you focus or target, the gold is the same.
If you absolutely must keep this mechanic, then keep it, but make the average hero kill bounty the same as before, so this insane gold inflation is gone and the enforced comeback is kept.
As for snowballing, just revert to the old system and increase the spree bonuses, so killing a snowballer is a bigger deal.
Honestly, I quit LoD for the time being just due to the insane gold inflation this caused. Casters were already not too good, now anything that is not a brutal lategame carry is worthless, since gold pours in so fast.