Every class has weaknesses and strengths, you need a variety of different classes on the field in order for them to cover one anothers' weaknesses and bolster their strengths.
2H do well in chaotic situations, as they tend to be the most well-rounded weapons (mauls aside), and so have few weaknesses on their own, but because of this they also have few real strengths that they can lend in group fights.
Mauls obviously have the very slow speed and very short reach, but hit extremely hard and have the crushthrough.
"dueling" polearms are similar to 2H in that they have few weaknesses, however they tend to have more utility roles (shieldbreaking being one of the most prevalent)
2 directional polearms tend to have long reach and extremely high damage, but lack sideswings, and often have poor overheads. Due to this they often have more difficulty than 2H in dueling situations, but have more use in a team situation. Halberds and bills also tend to be extremely good support for pikeman due to their high damage overhead.
Hoplites have much more range and ability to survive in close quarters than standard 2D polearms, but lose a lot of the damage potential and speed, so generally are better off as pure utility. (stopping cav, protection from archers, etc) They have very very little ability to duel, and not nearly the ability to harass as a 1D polearm. but they can fill far more roles than any other class.
longspears are far better at dealing with cav than pikes, and are (for most people) better for dueling, but lack a lot of the potential in groups due to their inability to safely curve around moving teammates.
Pikes are the ultimate support melee weapon, due to their incredibly long reach and ability to curve around teammates, however in order to get this they are also the slowest melee weapon (LoC excluded due to inability to thrust) and have unbalanced combined with this, so their thrust stun is an absolute pain in the ass for the user. Additionally they have only 1 attack direction, so any fool who knows to block down (5% of the population it seems
) will have little difficulty beating them in 1v1 unless the pike user has a ton of experience in dealing with 1v1 situations. Not to mention that the 300 length slows them down by a LOT, and their thrust only attacks makes guessing their movements a piece of cake for ranged.
It seems a lot of people really undervalue how excellent ranged can be at dealing with tight formations, such as pike walls. In battle shielders tend to run around with very tough shields, so breaking them with archer fire isn't really an option, in strat however shields tend to be much much weaker. Ranged in strat is an incredibly effective counter to heavily melee focused formations.
Cav are useful for picking off unaware enemies, taking out archers, and dealing with lone players, as everyone knows. What I would say, personally, they are even more useful for is simply distraction. One cav running around behind an enemy formation is enough to break their support's concentration such that their melee can break through, more cav is of course even better for this.
Every tactic, every class, every plan, every strategy has a weakness. It's not up to the devs to nerf something because you didn't want to examine your enemy's strategy and find this weakness. (I mean this for more than just the pike formations, and I'm not aiming this at anyone in particular, so don't go getting defensive.
) If there is a gamebreaking imbalance, as there used to be with the longspear and pike, THEN it is up to the devs to fix it, currently I would personally say the game is quite well balanced.
Oh, and I'm writing this after having stayed up all night played ME3, so if I said something incredibly offensive or stupid, I apologize, I'm about to fall asleep at my keyboard.
