[QUOTE="iMPACT! Player" Riaku;2411671]Really hated, but I mean REALLY HATED how badly Gohan's character was messed up following the Cell saga. He was a total badass. Just watch Bojack Unbound. How could you, Akira?[/QUOTE]
First off Bojack was a MOVIE, it has no bearing on the anime whatsoever as the Manga is what the anime is based off of. Second I agree with you, but this is Japan we're talking about, for all we know they loved it. You also have to consider several things.
1: Toriama planned on ending it after Cell Saga leaving Gohan as the hero, he was forced to come back which messed up the story(once again). He then came to a realization as hes said that Gohan wasnt really suited for that position and everyone still wanted to see Goku.
2: For the characters and the story it makes sense. After Cell saga they though it was the end because as Goku said his enemies will no longer come to Earth to fight him. Gohan at this point just wanted to become a normal kid and so this is why he went to HS and tried to be one. He then wasnt able to help himself due to his past as a hero and so he created a hero persona to fight crime(Smalltime yes but he had no reason to suspect anything bad would ever happen to him again). Also Gohan hadnt trained in years due to the same reasons.
3: Once Buu and the others came Gohan was weaker, this was also aided by him being drained at the tournament. So when he fought Debora it made sense that he wasnt able to beat him to a pulp, especially considering Debora was probably stronger than Cell. Also Buu, your new bad guy to arrive had just come onto the scene, so what was the best way to get him over? Thats right, brutally beat the hero of the last saga and the god of the universe to a bloody pulp and outperform him in every way.
Also you must consider that Buu makes Cell look like an insect, there is no feasible way to have Gohan stand a chance against him, thus his loss makes perfect sense. Also it makes perfect sense as to why Vegeta(even though he would later be beaten brutally and forced to blow himself up which still didnt work) and Goku stood a better chance. Goku had been training in Heaven with fighters from across the universe and created his Super Saiyan 3 and Vegeta got a big power increase from the Majin symbol.
4: And heres one that works against the whole "Gohan was reduced to a pussy or was ruined", he became THE STRONGEST CHARACTER IN THE SERIES. He was made a huge part of the saga and was thought to be the most powerful by Supreme Kai and their last hope of beating Buu. Gohan then pulled the DBZ version of the Sword of Superman, trained with it, released Old Kai and went mystic. When he returned it was like SS2 Gohan vs Cell all over again and he brutally beat Super Buu until he absorbed a SS3 and Picolo. So it took Super Buu with an SS3 and Piccolo combined just to put Gohan down.
Gohan would soon be absorbed and die, but I feel that Toriama did a good job throwing this curve ball into the series and making the ending about desperation and pulling all of the stops just to beat Buu rather than a superior fighter stopping him. It took literally everyone and everything to stop Buu, including the Dragon Balls after Buu grabbed the massive spirit bomb and decided to run towards Goku with it, which really brought the series full circle, because the Dragonballs for which the series is named for were once again important.
So I dont think they really messed up. Sure it would have been cooler to see Gohan grow up to be just like his father and be the hero of the Earth, but in the end it doesnt matter. Goku flew off to train the reincarnated Buu(Uub) as the next guardian and the series ended.