NEM had the great potential of being the first Trek movie about Romulans and I think it failed because it did not focus enough on the Romulans.
I also think that the villain with the monstership pattern which started there made the Romulans look far too weak.
And yes, I am perfectly of the irony: whining about missing the chance to do THE epic Romulan TNG movie is a fanboy critique.
So yeah, I don't wanna generalize and imply that fans suck at writing, e.g. during Piller's open door policy fans submitted great story drafts.
And of course it is unfair to merely focus on the plot and criticize STID as being too much of a copy job in this respect while totally ignoring that the texture and atmosphere of NuTrek is entirely new.
But I also think that two movies which heavily borrow from what came before are enough, now everything is set up and you could do your own thing (this was basically Kevin's thesis in another thread, view ST09 and STID as "setup" movies) yet Lindelof indicates that the next movie will not be different in terms of standing more on its own feet.
Let's not forget that the most popular was also the most radical Trek movie, there were quite some paradigm changes in TWOK (and while some like the stronger emphasis on Starfleet being a military was only used in the two Meyer movies the way spacebattles were handled remained virtually unchanged during the next twenty years).