I'm happy you guys have found the glorious siege server
I remember keeping an eye on the flag in my full armor. Every few seconds I'd take a gander over at the flag and notice there was one or two fewer people guarding the flag, and I atttributed it to people getting bored and running off (were those bodies always there?). Finally, I get annoyed with people constantly "leaving" the flag and start typing a small essay in chat to get people back on it.
And that was when I got roflstomped by 3 people who were sitting around the corner ganking all the unsuspecting defenders until they finally finished me off (who was the farthest away from the flag, and also the heaviest armored).
I notice the same thing on EU2, but it's good that you start writing that essay ;) dont forget the caps and use a lot of curses!
Usually there is always the same people staying on the flag while the rest goes front ladder, even on castles where it is beyond retard to leave the flag in the beginning of the round. If people still think they should run off, wait untill you see the first sign of an enemy and then start spamming 'FLAG FLAG FLAG FLAG... FLAG FLAG' (you can prepare a full line of 'FLAGS' and press enter when it's time.
People think people staying at the flag don't help the team, but they don't understand that without them every round would be over within the first minute. Killing a guy on the front wall is as useless as it is easy as he will just swing his weapon into your face again after 10 seconds while you have a 30 sec respawn timer. Unless the front wall defence turns out to be unbreakable, it will also turn out that people that stayed on the flag end up topping the scoreboard.
Every map needs another approach both for defenders as for attackers and every round you should change your tactic. Not just you, but with your whole team doing the same thing. I think teamwork and coordination in siege go beyond a much greater level than the 'stay together' or 'hold this hill' type of battle situations.
About the STR crutch builds on siege: put a few maulers on top of a ladder and it will indeed be untakeable, but have a few smart runners breaking a backdoor and taking the flag and the guys on the front wall won't even notice. Every build can do his thing, if you can't kill a lot of people you can still decide to capture or defend the gatehouse or to use your speed to push through defenses.
