I'd rather see a more curated experience as well, but I'm not sure how they can do that and maintain balance in the arena. Simply removing sets will just make the card pool better overall, it doesn't really solve the curvestone problem unless they tackle it in a more precise manner.
I'd rather see Arena become a more hands on experience for Blizzard even if it's more work. Rotating sets are an idea, but that might introduce too much of a metagame feature that might not be welcome. For example, currently you pick Warlock if you can due to their ample comeback mechanics. On "Classic + GvG" day, you should pick mage because mages were strong then. That seems like something they'd want to avoid.