I disagree with you saying the highest level champ only at 50 is not a problem.
You say "it's Bronze 2, he should do that without lvl 60 champ". And what comes after he has done Bronze 2? How far should he climb without lvl 60 champ? Bronze 4? Silver 1? Ok, 60 victories to the player, 60 more Bronze medals. Would that change anything? At least in Bronze 4 or Silver 1 he has to build a good arena team. Or do you want to see Lvl 50 Warpriests in Gold?
The players that flee because they can't build an arena team would flee 2 or 3 weeks later.
It's PvP, your opponents in arena are teams built by other players. Why should they be weak? Unlike the PvE-opponents, in the arena they want to win to. They get arena points if they win, and the they lose points if you win. For each victory a player has in arena, another player has to lose a fight. As there is no draw in arena, allways, whatever Plarium does, 50% of the fights are lost by one player. What else than "git gud" should be the solution? Weak built bot-teams that lose and make every player happy?