Gimli started out okay in FOTR, as there was some balance between his comedic and serious moments. For example, his reflection on Galadriel's gift showed a character that was starting to grow/change.
When rewatching that scene I thought, "if only he would have burped!?!" (I suspect that he
will in the 25th anniversary edition
).
By TTT things started spinning out of control and by ROTK we have the short Clown who couldn't utter more than a punchline. I'd accept the drunking and body counting accountant if - even by accident - we got a scene in ROTK in which Gimli wasn't a caricature. The scene in TTT where Gimli tells Legolas to 'let <Aragorn> be' was great as Gimli appeared to be thoughtful - not sure how it slipped it.
As others have noted, I assume that PJ sat in a theater during the showing FOTR, saw what got the giggles and thought, "we need more of that!" And from information regarding the size of the Witch-King's mace and the clay on Gimpy Gothmog's face, the staff/writers may have thought that they were
way over the top and so PJ would reject what they had submitted in jest, but...
And I would agree with others that as a viewer I should be permitted to have a serious or 'tear-jerking' or sad moment that is not interrupted after 10 seconds by some giggle.