Have you ever played bard?
You know how Bloodletter gets to 'skip' its cooldown right? Its based off your Dots 'critting'. Your dots critting are based off your crit chance. How much 'more' damage are you going to do using Bloodletter 4 times vs only 2? How about Repertoire? Same thing, its based of your dot critting, which is based off Crit chane. Does Balance help that? No.. Spear does. A Balance cycled for the 150% boost effect to use on a Spear helps even more.
But Wait! only Astro has RNG right?... So... i guess im just imagining how a Spear can actually help a Bard do more DPS than just a generic Balance can?
How about when your doing that last wall-to-wall pull in a dungeon and you want to make sure you dont have to wait for Mana before the boss fight? AOE Bole once the tank has all the mobs in a pile and relax a bit as you dont need to have your finger hovering over insta-cast heal for when that Samuri or Ninja gets hit by 5 overlapping AOE attacks they didnt see because there's 20 mobs all piled up in one spot.
And Ewer. Saying its only useful if someone messed up? I guess your saying its only useful if a Healer isnt in that 0.01% of meta-players that know 'exactly' when to move and the 'exact' spot to stand in 100% of the time and 'never' makes a single mistake? Isnt that basically calling 99% of the playerbase idiots that dont know how to play without dying?
The other cards 'were' useful, IF you understood more of the other classes in your party than "oh its dps, so he does damage, the only card he's wanting is one that makes his damage higher and Balance is the 'obvious' choice for that".
The Bard example is a perfect one. Sure.. Balance makes 'all' their attacks hit just slightly harder than they otherwise would. But a Boosted Spear helps one of their skills be 'able' to be used more than it otherwise would have, so instead of just hitting for 20 extra damage, you get a full 200+ extra damage you otherwise wouldnt have had. Then you have the Repertoire effect, which gets absolutly 0 help from Balance, but gets a direct boost from Spear.