I don't know about "most players". If the games were adequately rewarding, I think people would stick around. The problem is that most people have a purpose - getting currencies to get upgrades - that they want the fastest route to that, often with the least amount of effort and mathematically it doesn't make sense to drag out a game if that is your end goal.
Speaking personally, I play for fun and those back-and-forth battles where the outcome can change based on play are some of the best experiences I've had in this game. I know several in my circle are the same, and those who have quit because the game no longer has anything for people that want to be fighting for longer than a short skirmish.
Ideally they would cater to both crowds. Short games can be arena and the smaller battlegrounds, and long games can be the bigger ones. They're in separate queues so there is no excuse to only cater to the instant gratification crowd (when actually the latter are probably the more valuable players anyway).