Kazaa,
WW1 arena was a nice addition to the AH2 arenas. One could make arguments against a number of current arenas, but for those that enjoy those arenas, there can be no convincing that HiTech should abandon any of them.
First of all, there are new damage models and pilot head movements, not to mention an entirely different flight model system, that were all developed for the WW1 arena. At some point the resources developed in / for that arena may very well become a part of the Main Arena's future upgrades.
A good portion of the Main Arena wishes have been directed at re vitalizing the current game play aspects. If folks were given a glimpse of the future through upgrades in WW1 arenas or other arenas, transitions into Main Arena future developments, could go over smoother and even be anticipated. For example, I and others may now be excited about a future damage model for WWII models.