I just realised that some of the marketing material for this movie have the movie being set in the 2030's, the movie however makes no refererence to the year and technology on Earth seems to have not gone pass 2014.
So I'm just gonna guess that behind the scenes they figured it would be too time consuming to CG new tech and detail, and just removed all references to the date last minute.
Also a lot of the trailers and ads allude to Watney having a wife and kid. The trailers are a lie. (It's not the end of the world, but I've just never seen ads be manipulated in such a way before. It's just rather odd that someone would do that. It's not like they cut the wife and kid out, it's just not Watneys).