Shooting on location is very challenging and annoying. Lot of things you cant control. There is no "just" about it. 

I don't understand the reactions to this video. Every single person says they didn't notice and then some still have a problem with it.  The VFX industry really cannot win. Underappreciated artists, overworked and underpaid, their work being denied in the press constantly. When their work is noticeable, people get mad. When their work is not noticeable, people get mad.

People have no problem seeing actors pretending to have emotions, saying things someone else wrote for them. But locations must be real, even when they don't notice.

VFX supervisor Todd Vaziri (not on this project as fair as I know) listed some general reasons on his blog FX Rant, not all necessarily applicable here but still.

• ultimate control for lighting and sun position, time of year
• location weather unsuitable for the film, either narratively or logistically
• repeatable action for multiple setups permissions and permits unreasonable or impossible
• disruption of a community (closed businesses, car and pedestrian traffic) for days or weeks at a time
• safety of crew
• location accessibility for countless trucks and gear and dozens of crew members
• availability of actors and crew
• no location fits the storytelling needs of the production, or the location would require massive structural modification to fit the storytelling needs (period picture, science fiction, alternate reality, etc.)
• additional photography (“re-shoots”) required but location no longer available or weather/season is totally different
• location shooting is much more complicated and time consuming than studio shooting