While the arena can never be expected to be a main focus of the player base, just by virtue of the fact that one cannot always fly his favorite plane there, I believe it is more than the limited two country planeset that keeps the arena from reaching it's full potential.
Of the two types of CM run arenas, the AvA needs more tools to be able to function correctly.
The SEA can operate with limited tools because it is only open for one night events that can be structured and overseen by CM's.
The AvA needs to be able to run on it's own as a 24/7 open arena.
By virtue of the fact that a win the war reset function cannot work within a system of custom arena tables and map usage, the arena has a tough time finding it's place in the community.
The AvA is and as far as I know always has been missing the one key element that allows an arena to function on a 24/7 basis. An automatic basic strategic objective.
With out that, it will always be one of two things, a limited planeset dueling arena or a quasi special events arena, no more.
While an objective of base capture may be the best strategic element in a densely populated arena, a smaller arena might benefit from some other parameters for winning the war.
Even designating number of enemy destroyed as one factor could allow the furball to contribute to an overall strategic game.
The arena could also benefit from a modified perk system. If the CM's could price their own perk rides on a setup by set up basis, the points awarded for war wins could sometimes be spent in the arena.
Some set-ups could not use perk rides, like Battle of Britain, unless the pure historical concept was modified to allow a perked Spit 5 or 109F, but on several mid to late war set-ups perk rides could often be added.
The question is how difficult and how much resources would it take to modify the code to allow these CM options?
I would contend that while CM run arenas will never be HTC's bread and butter there would be some benefit to the company in directing some development to it.
One would simply be customer retention. More options = more reasons to stay.
Another would be by coding more flexibility in arena game play set up, the creative use of such by CM's could serve as a beta test bed that could lead to ideas that could enhance the game overall.