It's been a while...
I stopped playing about 8 years ago for a variety of reason including burnout (but I have stayed a subscriber to support what is IMO an important niche - the accessible WW2 air combat sim with a focus on realistic flight models). Actually looking to start back up again and I've made a few hops and scored some kills.
While burnout was a factor the "win the war by winning the map" gameplay mode which is still around was a much bigger factor. Time spent looking for a good fight way outweighed the time spent actually having a good fight. Horde warrior is no fun getting gang banged, and for me no fun being part of the gang bang. This is about the 10th time I have posted the following (but not for 8 years) but I believe it hits the core of the issue. There do seem to be more fights now than when I checked out (maybe because some of the casual gamers have left), but there is still much of the same.
FWIW this isn't unique to AH. I left Air Warrior a few months before EA shut it down for the exact same reason. Going way back, though a few years short of Dale and Doug in this regard, AW started off as a combat sim that while it lacked in graphics, and lacked in flight and gunnery models did not lack in fight. Winning the war (not the map, more on that in a bit) was still there but the fight was always on. I took a year off from burnout in the late 1990s or so and during that time the win the war model changed to win the map. The very FIRST flight back was spent chasing planes trying to get in a fight as they made suicidal attacks on fields or milk ran in odd corners only to relocate if any opposition showed up. Sound familiar? It was so dramatic a change that it was immediately noticeable and like an entirely different game.
When I came to AH for the first few years it was like early AW where the fight was concerned even with the AH map focus. That changed, I believe with the first "massive squadron" developments (Thanks Rip!) and huge typhoon raids. It was as if no one had really conceptualized winning the war vs winning the fight until then, and it was a natural outlet for the newer players coming into the game for the early AH marketing efforts.
ACM is much harder than a FPS type game. Becoming competent in 3 dimensions, blackouts and redouts, energy management and most importantly layers of situational awareness takes time and effort. It took me about 6 months in AW back in the day flying against guys who were really, really sharp to finally get a positive KD and that took not just practice for skill but some key conceptual insights as well. For people that grew up reading WW2 books on air combat and the great aces the brutal failure was worth it for a brief glimpse at that experience. For the typical gamer without that connection to history I can only imagine it gets fairly old fairly quickly. More acradish flight models and view systems overcome this to some extent. But, an even better shortcut is the ability to succeed at winning the war vs. winning the fight. And winning the map allows for that.
In AW's original model only the central fields were capturable. The "atoll" for the Pacific map and the "Lake" for the euro map. The rear fields for the countries were not capturable. Points were scored for the amount of time a country controlled the various central bases (which switched back and forth) until the tour timed out a week later. Why this model works is that in order to capture the bases and eventually win the war you HAD to congregate in a central area. That area was big enough for one country to push against another or to fight over a specific base, but small enough that it was much hard to avoid the fight and harder to generate lopsided numbers in some corner of the map during normal hours. Milkrunning did occur but that tended to be in low attendance hours.
The change at AW happened during the Gamestorm era which continued to EA which was sucking big time 20 years ago as well as today. In speaking with the customer support folk about the crash in fun and gameplay with the much more spread out win the map format they said that the pricing change that happened etc. (much cheaper) generated far greater numbers and that the server code could no longer handle concentrated numbers. I would imagine that might be an issue today but a lot of progress has happened. IMO, a return to a similar gameplay, win the war not map model would dramatically improve gameplay.