You may know counter strike. It was created by: players. Modifying/extending existing games is something that isn't too uncommon. Players don't "have to", but some seem to enjoy it.
This list is slightly short.
And two in that list were literally,
LITERALLY, designed in a previous century.
Look, I understand the design goals of a 3-sided war. I have nothing against it in principle. It never bothered me personally. It has advantages and disadvantages as a game design.
It's main goal was to provide a self-balancing mechanism. However, it was so inferior in that role, that HTC had to design and implement an ENY system to do the job better. That is a superior mechanism for self-balancing. And with that, the argument that you MUST have a 3-sided war is greatly undermined. AW never had an ENY system that I remember. It
had to resort to the inferior mechanism of 3-sides. HTC no longer has that constraint. They have a better tool now.
While the 3-sided design was not sufficiently effective as a self-balancing mechanism, by happy accident, it was very useful when we had 650 players in the arena because it tended to self-distribute the action. It was an elegant way to create more frontage surface area for a given map size and thin things out. However, that may now be working against HTC's interests, when you only have 160 players on the best of nights.
A 2-sided design would have the opposite effect. It would tend shorten the available frontage surface area for a given map size and increase player density along the front and create more action and a higher cadence of activity. At the same time, ENY provides the self-balancing mechanism to mitigate the degenerate tendencies a 2-sided design might devolve to.
The assumption that you MUST only have a 3-sided war was formed in a previous century, when HTC didn't have the self-balancing mechanisms it now has at their disposal. It might be worth honestly challenging whether those previous assumptions still apply in a new century, with a different size player base, with new, superior mechanisms for balance available to you.
The day a company starts refusing to constantly challenge their previous assumptions in an intellectually honest way, is the day it takes its first foot steps on the road to obsolescence.