In my opinion the 2D polearms are not great. They are pretty bad in a 1 vs 1 as they are rather easy to block and they have rather little reach. The awlpike is probably the best one of these, but there is not that much tricks you can do with them. Which means that when you are alone people are just going to block you and when you are supported they don't hold a candle to the longer weapons. You always have to be in almost striking range of your opponent, you are able to usually only really threaten one opponent at the same time and so on.
The biggest advantages of the longspear/pike are reach. The importance of this for supporting cannot be overstated. This might not hold for Australia but on an 80 player battle server, more reach means that you have so much more targets that you suppress in your average clusterfuck. Which makes these weapons extremely good support weapons, as you can shit on ten players at the same time, by forcing them to continously pay attention and be passive because you could stab them at any time. As for low damage, I think the slower a weapon is, the more it benefits from speed bonus. Makes sense because the movement speed is relatively large compared to the slow weapon speed. I have often oneshot people in medium armour with a 7 ps longspear, because they were walking towards me and I stabbed them in the head. Similiarly I also take like 4 stabs sometimes to kill a running archer in cloth. Stabbing someone in the face who walks towards you with a pike hurts fucking bad, despite the low base damage. If you learn to work your speedbonus you can get a really high damage output with both the longspear and the pike.
Also the extreme ability of the longspear and especially the pike, to curve around and stab through teammates makes it a very potent surprise weapon. You are able to end ganks extremely quick. The longspear gives you basic 1 vs 1 ability, the pike gives you nearly none. You can in fact kickstab with a pike. I was able to do about equally good with these weapons, but pike requires a lot more attention to your teammates. The pike is in fact so long, that most people don't even realize you can attack them. Few use the pike though on EU, and even fewer use it succesfully.
I think the longspear and hoplite are rather similar. Ashwood pike is a little shorter, slightly faster and I think ashwood pike hoplite does just slightly less damage, but does have a shield. I have long been a longspear user and I always thought of switching to hoplite. They were equal in the past, but with the turn rate correction, dunno if you have that in Australia, the longspear turns slower and the ashwood pike turns faster. Which has swayed the balance towards hoplite for sure now. The higher turnspeed allows you to stab easier, surprise people by switching target at the last second. It also feels more enjoyable, less sluggish and restricted.
I don't know how much players we are speaking, but with the old turnrate, which means the same turn rate for every weapon. The longspear is the best weapon. I don't know how good you are, but if you learn to use this weapon correctly you can wreck some serious shit. If you even only stick with one teammate, you can already be a gamechanger. The key is battle awareness and learning to kickstab. Stabbing in general should be an up to down motion to minimize glancing. If you have the new turnrate, ashwood pike hoplite is the best. Due to more turning up and down stabbing is not necessary, but still the best way to do it. With lower player count I wouldn't use the pike. If you get in a 1 vs 1 you can kill someone quite easily with a longspear. With a pike it is incredibly difficult.