We had some nerdy formation experiment some years ago, think Guard_Tristan organised it, where like twelve people gathered on a server to practice moving in formation and fighting while maintaining formation.
We then took it to EU_1 and got completely wrecked. We moved in a semi circle shield formation with half hoplites and shielders and behind that we had a piker and a few great mauls for damage dealing. Moving and fighting in a formation looks epic, but your enemy doesn't give a shit. What happens is as soon as you charge, enemies run away because they were scared to take on a dense group, which meant that we basically fought with no one all round. Only when our formation was thinned out by ranged that just encircled us and all of our teammates were dead, we would get charged and quickly overwhelmed.
Battle size is too small for formations to have any use and would only work if both teams would have formations that could clash. A formation moves too slow to catch any enemies and people are going to avoid taking you on. Also when we did get in a good fight we performed poorly because we were constantly paying attention to the formation instead of actually fighting. It was a fun experiment and it allowed us to firmly conclude that actual formations beyond just sticking together loosely are useless in cRPG.