not sure how helpful nowing subscriber numbers really are. There are so many factors, I would imagine anyway, that contribute to subscriber base. Economy certainly plays a factor. Other factors that may contribute, gameplay, time of year, community, game changes, interest in genre, advertising, etc. We also don't have access to complaints filed, noob retention, or vet burnout. Maybe HTC views larger populated arena's to be "unruly" and worries effects won't just cause people to not sign up, but eventually cause larger sub loss. Numbers and charts are great, when you have all the numbers needed to really make any sense of it all, imho.
I do dislike the large maps with less people (actually never liked the large maps at all), and sometimes it's a annoying trying to get into the arena you want. Don't fly all that much anymore, but in the times I have, can't say I've had more fun on Tuesday. In the past I've really liked the idea of the split arena's, not really sure of what opinion I have now. 200 generally seems about the same and I can't remember if the swarms were worse. We've also had other gameplay changes since.
I don't see the arena's "ruining" the fight, players do that. Though I don't think the larger maps encourage fights.