I wonder if there is somewhere on the internet a list of lessons with botched deliveries. I've certainly run into such lessons in the past. I'm just drawing a blank on what they were.
The latest such example I've encountered is in Shin Mazinger. Main character Kouji is cocky, brash, and his desire for revenge causes more problems than it solves. He also likes to do things himself, without relying on others. This is an attitude that the other characters try to fix, so that he will begin to work with the other robot pilots.
The lesson of relying on others is learned in episode 12, when Kouji is held captive by Baron Ashura. Alone, captive, and with no visible means of escape, Kouji finally realizes that he does need to rely on others. He has learned a valuable lesson.
Except...
A big part of why Kouji acted as a loner for so long is that the other robot pilots are worthless.
They can't even damage the enemy robots, much less defeat them. They contribute nothing to battles, excepting the five seconds that enemy robots spend to destroy them every time.
Heck, they aren't just worthless, they actually interfere with Kouji's fight. Kouji learned the lesson of friendship and teamwork because he was captured? He was captured because Sayaka fought, lost, was captured, and was imprisoned in an enemy robot. Kouji could either kill her along with the enemy robot or surrender. If Sayaka had never gone out to fight in first place, Kouji would never have been captured.
Or take the end to I think the first battle. Kouji, who wants to kill Baron Ashura, has Ashura held within Mazinger's fist. The other robot pilots, wanting Ashura to be captured alive, attack Kouji, which in turn frees Ashura. They then hold Kouji back as Ashura escapes. Kouji, undeterred, knocks them all aside with Mazinger's beam attack. So Sayaka, who wasn't involved in the group tackle, intentionally jumps in front of the attack, forcing Kouji to choose between killing her and letting Ashura escape. (It should be noted that no one bothers to follow the escaping Ashura back to the enemy's main base. This is important, as being able to follow Ashura was the excuse the other robot pilots gave for preventing Kouji from recapturing him.)
If Kouji had been allowed to kill Ashura, then he would have never have been captured by Ashura later. Plus countless lives might have been saved, as Ashura later attacks several major cities, attacks which the other robot pilots are completely ineffective in stopping.
Should I even bother to mention that it isn't the other robot pilots that rescue Kouji from that cell? Should I mention that this wasn't even the first time that Sayaka was captured and held captive inside an enemy robot in order to stop Kouji from fighting?
The other pilots even being present in battle is a handicap for Kouji.
So, as I see it, this is a completely botched delivery of an otherwise meaningful message.