DRG was a failure -- they just sat around Jueno all day hoping for a party.
WAR was a failure -- they just sat next to the DRG in Jueno all day hoping for a party.
MNK was a failure -- they were only good in fast skeleton rush parties.
SMN was a failure -- they were wanted when there was no WHM around to heal the party.
RNG was a failure -- ammo was so expensive, RNG just used daggers all the time
NIN was a failure -- shuriken was so expensive they never used it, and just went as a NIN/WAR *TANK* O.o!
SAM was a failure -- they gave the mobs so much TP that it ended up hurting the party more!
WHM was okey -- they healed and that was all they were expected to do.
I think perhaps your definition of 'failure' needs to be adjusted. Every job had a positive and negative side. Every job was perceived differently in party, solo and NM situations. Every job was perceived differently by different people.
As for your argument of not casting spells: Were you not Magic Bursting? You KNOW you can poke the mob with your sword at the beginning of the fight to get enough TP to help a skill chain so you can then MB on the skill chain (all whilst maintaining a refresh and cure cycle).