Every game have some characters that are worse than the rest and are the bottom of the barrel.
Well, given most of those character's (or the specific version of character) relevance to the story as well as the difficulty in obtaining them, it's not surprising that most of those are "it".
That said, I have no idea why itachi and jiraya is so weak. I mean sure, there are stronger versions, but those two chars aren't exactly weak even in the start of the story.... If Itachi immediately grant full chakra on the turn the barrier goes up, it would be a different story, but having its effect delayed a turn significantly weakens him, as turn 1 would have been the turn when it grant the most amount of extra chakra. 60+40+20 as it stands now is very lackluster.