Ok, there are arguments pro and against. I have to say I'm not a big FTF fan, because the "big budget => action & SFX" implication was too obvious for me.
- XF, the most cinema-like series in TV, got on the big screen for real
- XF was recognized to be worthy enough and strong enough to get a cinema release; not the same can be said of many shows... This kind of notoriety must have really given courage to the XF writing staff!
- Forced Carter & Spotnitz to sit down and really set things straight about where the mythology was going; sure, the mythology was made up as they went aong, but at least this way they had nearly 2 years planned ahead of schedule.
- was semi-successful financially: no, it wasn't a failure as some want to present it (didn't fare very good in USA, but overall internationally it was a net positive for FOX); no it wasn't as successful as FOX had hoped to either
- brought more viewers: who cares? if you were watching it, what's that going to bring to you?
- some say s5 was less better than average because 1013 conentrated on the feature. I don't think so: Redux I&II were excellent, Christmas Carol/Emily was different and beautiful, Patient X/The Red and the Black gave real answers to the mythology, many good loners as well (PMP, Bad Blood, Kill Switch, All Souls, Folia a Deux)... a fine season!
- Action, action and "Alien" rip off, and action
- blockbuster movie meant less mystery and more answers given; the mythology turned from mystery to pure scifi
- in terms of mystery, density and tension, many episodes actiually fared better
- XF got more mainstream, it definitely did in LA
- XF gathered enough momentum to continue for 4 more years... that's too much!
But after all:
- given that the success was there, Carter would have gone ahead with a movie anyway; that was his master plan, 5 seasons followed by a movie franchise
- and it shows! FTF is followed by 2 seasons which are much emptier than the previous ones mythologically (1 two-parter/season instead of 2, barely any substantial non-2-parter mythology eps)... Carter spead out the stories he wanted to do features on in 2 seasons, and ended up in the bad situation of having to create something new for s8&9...
So...in Carter's shoes, I would have chosen to do a movie as well, but I wouldn't have done FTF. Which is another way of not choosing.
Go for helped, with a long-term result of hurt.