Ya it was bad writing IMO too. Remember Gladiator broke Hyperion's neck (Hyperion as in the first Marvel Superman clone), he's fought Surfer and Ego the living planet at the same time (oops just read that fight wasn't in continuity, oh well), he recently took the eye of the third Summer's brother who's an Omega mutant. Gladiator is a badass all around. As shown in a Gladiator respect thread, he fought against a foe tossing Surfer and a few other high levels around and never for a second lost confidence, if anything an unbeatable foe made him want to try harder.
In the fight against Hulk he blew a hole in Hulk's chest, Hulk healed and Gladiator lost confidence...apparently. Then Hulk punched him like twice and threw him in a reactor.
Not taking anything from Hulk, but Gladiator's seen way worse and not lost confidence, he's taken harder hits and not been KO'd. So yes IMO it was made for the sole purpose of Marvel saying that Gladiator is Superman level and Hulk beats Superman. It hurt the character in a lot of ppl's eyes, and kind of stomped on Gladiator's past achievements. Hulk's a tough foe, but he shouldn't be able to two hit Gladiator, let alone make him lose confidence that easy.
It happened tho, the characters are all at the whims of the writers lol. Gladiator written as he should be with past showings should give Hulk a hell of a fight if not beat him. Thing goes toe to toe with Hulk for a bit, Gladiator has one hit KO'd Thing like it was nothing. Here's the Gladiator respect thread -
http://herochat.com/phpBB2/viewtopic.php?t=99852&sid=09613e42c2ec5ed2487bb458a14be8c8
Gladiator is supposed to be Pre-Crisis Superman strong, as in he's been said to move planets, and is said to be 100 times the speed of light by Reed.
So yes, IMO bad writing and a poor showing for Gladiator. Pre Crisis Superman Strength, 100x speed of light, planet moving Hyperion neck snapping Glad shouldn't be two hit KO'd by Hulk

.