I had the same problem in these days... but I think is connected to the matching system which struggles in finding a good match when there are only few players around playing arena in certain hours of the day...
I think it's a bit sad... People don't understand that arena shows the real skills of a HS player... it has become my favourite mode since a year or something and I am getting better and better (last two months I played 43 arenas with 6.3 WR) and gained a lot of packs, gold and dust for free!!
But I understand when you say you want a bigger pool of arena players, you mean that you need a bigger pool of plucking chickens... So this is why people leave arena, they have no skill
Never experienced the same issue on EU, too. Never had longer queues than maybe 10 seconds, and I played a lot arena in the last time. But I don't play off time, deep in the night etc. Mabye that is the problem?
But I mean, 14 hours ago is your post OP, that's not an off time. Maybe they have some problems with the matchmaking there.
Twice I tried to get a new Arena match and gave up after 2 minutes. Then proceeded to disconnect and reconnect and afterwards got a match within <10sec. I think it was some sort of bug and not lack of players