Why does the winning team need an advantage beyond levels, gold and objectives?
Typically in a sport, the environment is always neutral. A team that is winning in soccer doesn't suddenly get to field more players or get to force their opponents to wear ankle weights. The same is true for e-sports. In DOTA or Starcraft, the winning team doesn't get the environment reshaped to their benefit. So why will minions be given extra damage for a team being up 1 tower or being up slightly in levels? Remember: there's no limit. If everyone on your team is level 7 while your jungler is 6, but the enemy had a Shyvana or Yi that was power farming, they'd get the minion buff.
Now let's see what being up in a tower means in high elo:
It already means that you gain a huge amount of map control to freely deep-ward, catch out, steal camps, etc. You now pushed the boundaries of "unknown territory" towards the opponent's base. It makes ganking easier. It gives global gold. It reduces the enemy's vision.
As you see, these are HUGE advantages already, just from the loss of a single objective. What need is there to artificially make minions even stronger and kick the weaker team when they're down? If you score in soccer, does that mean that the opposing team has to wear weights on their ankles? No way. So why is the losing team now being artificially handicapped?
If you are unable to actually win the game in a neutral environment, despite the vast advantages given by an objective, then perhaps you simply aren't as good as you think you are. This is doubly true for the new queue system in ranked, where there is absolutely no excuse for "but my team of solo queue silver scrubs doesn't listen to me the challenger stuck in silver due to elo hell" because now you can control your own team to group and push for the win.
The other question is: where does it all end? If games are now essentially decided (at high elo) at the first tower downed, is it such a stretch that one day that games will be decided by First Blood or even advantages as small as 15 gold from Skarner shrines or 10 gold from Kalista sentinels? Would you want to play a game where you spend 20 minutes minimum playing, but you might be doomed starting at minute 1, due to some random thing?
This change, more than any other, in my opinion vastly reduces the quality of high elo games. The best games for both playing and watching is a back and forth, where the outcome is not decided by a single event but by consistently outplaying the enemy team and making dumb mistakes cost you big time because everything is on a razor's edge. That's a good game. A bad game is one where the game itself is so tilted that once you get the snowball rolling, you can play like absolute crap and still win. That's bad because then random events have much more impact on the outcome of the game than actual skill.
