Geoff Johns didn't move the needle on it at all, one way or another. I read the original script, and it was terrible. It was a terrible script written by mediocre writers, produced by mediocre television people. They got a director who is mostly passed his prime to do a kind of movie he had never done before that was fraught with serious hurdles naturally.
Geoff Johns maybe added a few nerd kernals to the thing, but the real problem was there from the start. Those people make shitty things (sorry, fans of Arrow and Flash)
That's right DONT SURRENDER!
But you're wrong. A lot of writers and talent get chewed up by the system. Great movies are made when the studio gives one part of the talent (actor/great director/producer) room to make decisions. Otherwise you have excellent Marvel films that on occasion hit it way the fuck out of the park (Winter Soldier/GoTG - Avengers (spectacle was half of that though))
In films that fail like GL or Goyer's Blade 3(had to bring up your fave if you look hard enough sometimes the writers are dead on but there are outliers.
Studio's get involved and you get GL. GL is a straight forward story - hero is a heroic and charismatic normal guy, gets powers, goes on hero's journey, end story. I can only imagine how much the story "demanded" to put in." I can't imagine any writer with a modicum of talent writing parallax to look and act like that, the forced romantic relationship, the giant testicle head Hector Hammond - it reeked of shoveling in executive demands
Even when that's not the case - sometimes a good writer will get a script going, modway through (and this did happen with GL) another writer is brought in to "clean up the script". which is Hollywood speak for pick up from where the now fired guy left off and mix a new writing style with plot points that are different than writer #2 wants and eventually, it's a move written by committee with predictable results
Goyer had an amazing plot and opening to Blade 3 (if I could only remember where I read the fucking thing) and say what you will but Goyer is a very good concept man with bad dialogue and third act issues - he works well with partners (hence Batman/Blade 1 and 2 and should have been 3 being so good while others are less so) Wesley Snipes had an absolute meltdown on set and most of the movie was filmed without him. Google patton Oswalt talking about this and check out the you tube outtakes