WOE allows you to explore and experience more aspect of the game itself than just PVM. It can be exciting a lot.
You also make more friends from it, though can also make enemies at the same time..
If you are benefiting from being in a guild that is actively helping it's members out (answering question to builds/ gears, leveling/ instancing etc together) it's just a nice gesture to give back a bit of time to help them in the WOE scene.
As far as reward goes, Castle loot has been crappy for a while and nothing has been done to change that. To complete the god pieces collection can take many months to years to complete, so the guild leaders themselves are the ones that often pull through all the obstacles to get to that end goal and don't just benefit off it through one month or two's WOEs. Whether or not they share their god gears/ profit depends on the guild themselves. Every guild is different.
I am a retired WOE player myself, because I'm extremely against a certain gear being implemented into the WOE scene that fell under the management's deaf ears, as well as the extremely stale WOE scene currently. I still participate in WOE TE though.
Just my 2 cents.