You are right in that the PvP decks have an influence on the market by lowering the prices of PvP only cards and mostly PvP cards, such as Giant Slayer or Scythe Fiends.
You have to keep in mind however, that other cards will therefore increase in value, because the average value of a booster will sonner or later fluctuate around their fixed market price of 350, as you can verify here: https://smj.herokuapp.com/boosters
This is just wrong, inappropriate and rude. It has nothing to do with boosting anyones ego. With the free PvP decks, everyone has the same chances of winning. If you don't make it to say the top 50, it is just because you are not good enough. And when you loose, it is because your opponent outplayed you. Getting good is the only way to climb the ranks, and this takes practice and effort. The knowledge you gain in PvE barely even helps in PvP, you have to play PvP in order to get better at it. If we go back to the old system - which btw was not optimized for fair play/fun but for making profit - people who farm more will win more, sometimes even against players, who would outplay them in an even match in terms of cards and upgrades.
The best PvP players are indeed the best, because they spent the most time practicing - just look at the number of games they player, its usually several hundred. I, who has played way less games obviously stand no chance against them. But this is also why we have a - admittedly flawed - Matchmaking System, to pair even players.