Why did Nolan change the portrayal of Gotham between 'Batman Begins' and 'The Dark Knight'?

Go watch them back to back; or like me and watch them over two days. Ignore the fact that Rachel Dawes is played by two actresses - this everyone already knew and expected. The really really strange difference is in how Gotham looks; how it was presented between the two films is like night and day.First and foremost, I love the whole trilogy. I'll be honest though, I thought the way Gotham felt like its own distinct city in the first film was nice. It was a bit noire-ish, maybe; definitely a modern-day dystopia - I quite liked the idea of it. In the sequel, the city feels way more reality based, this isn't bad either really - as a standalone film, seriously I don't have a complaint. But watching both back to back as a whole bigger picture story, it's actually kind of hard to say that they are set in the same city... There also is a glaring lack of the rail system that was in the first movie.I'm trying to picture the events of 'The Dark Knight' in a darker, more modern-dystopian Gotham like in the first movie and can't think of why they changed it so drastically. I can't really say it takes a ton away from the films, I really like them regardless, but damn the difference is pretty stark.As I remember, the city in 'The Dark Knight Rises' very closely matches 'The Dark Knight'. I guess I'll know for sure when I watch it again tomorrow.And a final aside, if you remember the ending of the series where Blake (Robin) ends up in the batcave - what are the odds that Nolan picks up again in this universe and makes a Nightwing movie? Probably 0% - but boy, could that be fun!E: what I forgot I realized is that the Joker in TDK says that a year ago, the mobs owned the city. There's the timeframe between Batman Begins and TDK. via /r/movies http://ift.tt/2njHEvI