Arena:
IMHO, it's completely fine. Compared to HS definite kick-out at 3 losses leaving you with potentially just a pack, there's at least the chance of a 2-3 or a 1-4 with gold returns. I think of arena as basically pack + potential value, since that's what it is -- it's the same as real-life drafting, where you want to play to probably get some more experience and understanding of new cards while also getting a pack in return.

Also, I think all classes are decently balanced enough in Arena, with some just a tad more consistent that others. Going 2nd definitely does give you a huge advantage, so people are hoping for a balance change in that area.

Vials:
Same here, not too much of a problem. Sure, you -do- usually have to get to 3 legendaries and that -is- 10,500 vials, but that's what you get when you save up for packs/arena and keep playing the game over time. Alternatively, you might want to reroll at the start for a specific legendary for a deck you want to use.

If we're talking about being competitive early on, you don't even need that much vials. People can make competitive Banner Sword, Bat Bloodcraft, and Haven even under a budget with little to no legendaries at all (trying to point out that not -all- competitive decks need triple legendaries). People optimally liquefy stuff for the decks they want, anyway.

Also, TBH, I'd say other games out there have a worse grind in terms of gold and vials. At least here you have a set amount of daily quests that can add up to over 100 rupies or a pack per day.