Perhaps the reason people feel this way is because they didn't watch the History of Trunks special midway through the saga like they were supposed to. To me, that provided plenty of build up for Gohan, given that he fought the androids for so many years and trained trunks and gradually got beaten down until he was eventually overwhelmed.
That would have been a sort of lame use of the death of the main character of the series, though. Goku's death provided a bit of final emotional weight to Gohan defeating cell when all the chips were down. It would have been kind of lame if a character who had been in maybe 30 episodes total of the entire series stretching back to dragonball provided the end to the saga moments after Goku died.
I think that the Trunks special kind of double fucks up the Android saga, since Trunks himself doesn't help a lot in the saga (until he goes back to the future).
If you see the Android/Cell saga as Trunks' story (and why wouldn't you? He is the one who starts it by killing Freeza, and then you have this whole OVA centered around Trunks and he is the one moving the plot) he should have some very deep developments during his stay in the past, but the way it plays out, FTrunks does some very dumb things, and ends up being killed by Cell. He makes acquaintances with his father, and that's it.
So, if you saw it as the history of how Trunks met his father, Vegeta saving him would have been a great plot development. Instead, it will take until Buu to have Vegeta hug Trunks. Which is another reason the Buu saga is awesome!
I do not think that the History of Trunks saga centers so much on Gohan's failure, as much as it centers on _everyone_ failing at stopping the androids. Gohan just happens to be the survivor, and his death triggers Trunks SSJ (IIRC?) but the blame falls on all the Z-warriors except Goku, and the plot points that it might not have happened if Goku had lived. It is the main reason Trunks carries medicine with him.
Also lol at assigning Gohan and Trunks finding the Cell coccoon together having any deep narrative meaning. Young Gohan and Trunks barely interact at all during the saga, which is ridiculous for a time traveler who meets a younger version of the beloved master he saw die. Indeed, as I always say, FTrunks and Young Gohan not interacting is one of the main problems with the Cell saga, and one that undermines the idea that the android/Cell saga was all about Gohan. Even FTrunks didn't give a fuck about Young Gohan.
Also also, look at how Gohan's SSJ2 transformation is triggered. Goku goes SSJ due to Krillin dying, Trunks goes SSJ due to Gohan dying. Gohan himself? SSJ2 due to an android he never spoke to dying. I think they didn't speak before? It is super dumb anyway.
If Trunks death didn't trigger Vegeta's SSJ2, at least get me Gohan go SSJ2 seeing Trunks die. It would have mirrored History of Trunks perfectly!. Maybe it is because Toriyama didn't write History of Trunks, so he didn't feel the need, or saw the logic, of his android saga mirroring this OVA he didn't write. Of course that also would have been lame too, given how FTrunks and YGohan only hang out for the Coccoon discovery. Oh noes that guy I've spent with almost an hour died aaargh -> SSJ2.
Cell saga requires a ton of rewriting to work as Gohan's coming-of-age story.
