PArt of the increase was Production ide still gaining mroe less on what worked and what didn't work, but easiesly the biggest was Piller.
Piller changed dramatically the focus of the show, to "it's about the characters" as opposed to about what's out there.
And while you don't see his name on many of the scripts, he has stated (and many times) its the most uncredited rewriting he has done in his entire life. Head writers are generally the last place a script sees, and a head writer can rewrite any script, often uncredited).
I am sure Behr will take about the utterly brutal hours they put in (and why he left Trek).
Piller huge, huge huge influence on almost every single script (once he took over), Behr (an experienced tv worker who also helped on rewrites), and two hugely important new writer in Moore and Echevarria who's influence on TNG was huge (though in fairness Moore and Echevarria influence in later seasons is much, much more profound.