The big problem with dealing with the other classes is that they all counter Midnight Blade as well.
Earth is immune to damage, puts up shields, revives, interrupts, he's everything a DPS ninja hates. We want you to die and stay dead, preferably as soon as possible. Currently it's hard to see earth's effectiveness because there just aren't a lot of crazy Earth ninjas. But rest assured, the full Pain teams are coming. Mass buffing resistance/defense, mass shields, mass power increases, reflecting status effects, healers that cleanse twice per turn, Earth team will be invincible.
Water has the ability to heal like crazy, removing debuffs and restoring the damage we just did while potentially throwing sharks at us at the same time to trigger one of Water's famous ludicrous hit combos. To top it off they usually have healers with them because of synergy, making it all the harder to finish off anyone.
Wind is our mortal enemy. That AOE power will basically half-kill our entire team and completely kill one person due to a combo. This is because Lightning teams tend to run - you guessed it - Lightning ninjas. Which are extremely vulnerable to Naruto and Main spam. Plus the Wind main's jutsu fires TWICE, effectively spelling death for any team that doesn't have control for her. Defensively, what do we have to deal with? An army of clones.
Fire is just annoying on all kinds of levels. The easy access to burning damage is one thing. But a standard attack sleep, lowering defenses, multi-target AOE ignition, and a silence too? Lightning does not like status conditions, that's why we have powers that make our swordsmen immune to them. We depend on combos, damage, and some healing to survive because our main is made of tissue paper. To top it off, using our own status effects like the Paralysis or Acupuncture is likely to retaliate on us because of Mirror.
Oh and the best part... despite people saying they can't seem to interrupt a lightning main's chidori, Fire and Wind mains always seem to act before us. The combo already went off before the paralysis took effect.
This game isn't about combos, it's about health bars. Burning, AOE, and healing are extremely important aspects of managing health bars. Right now you just don't have ninjas fully upgraded so everyone seems kind of squishy and dies to burst combos. That won't last forever!