The upside is that you can get 1000+ feathers fairly easily-ish from the arena. Who knows how quickly the arena meta will become complete locked down to only top-tier, maxed out stuff*, but for now it's not THAT difficult to rack up decent points by fishing for a win on a hard difficulty and then padding out your streak with easier wins. I don't know how long arena seasons will be, but this one was only a few days, so if they're a week-ish feathers should rack up quickly. Even getting to that 20k won't be THAT hard if the seasons are short enough.
*Does anyone know how arena matchmaking works? My guys are level ~27 and I never see enemy teams that are THAT much higher or lower than me. Does it match similarly-leveled people, is that just where most people are in the game at this point, or does it adjust enemy levels?