I'm totally for a fabric suit, but it would have to have armor underneath. To me, that is a vital part of the character. He has worn the minimum of a bulletproof vest under the costume since Batman # 1 (1940). Bruce is only human. However, I cannot stand the Dead End costume and I feel that fans who bring it up and other fanfilm costumes are actually doing the fabric argument a disservice because they do not look believeable whatsoever. I also don't like the idea of nanofiber/liquid body armor. Yes, it is based in reality and only a decade or two away, but, in my opinion, it lacks the dramatic potential of a fabric body suit/more traditional underarmor design. I just don't like it. It just doesn't suit my visual sensibilities and understanding of the character's history.
For instance, I love the shots in the comics where Bruce is shot or injured is some way and the body suit is torn or ripped away to show the armor underneath. Or shots where he is undressing in the cave after a hard night and the shirt half is removed to show an injured Bruce painfully removing his damaged armor. (kinda like a football player taking off his pads after the game)
However, I think some are misunderstanding the fabric suit doesn't fit Nolan's world argument. While some are right that if Nolan had gone for fabric from the beginning, most of us would be recanting on that point, that counter doesn't make sense at this point in the story. Nolan has already established a certain aesthetic and certain story reasons behind his choice of suit. Switching to a nanofiber/spidersilk/liquid armor batsuit at this point would be too big of a change. Yes, perhaps, after meeting Bane, Bruce decides he needs to be even faster, but it be too big of a jump. He already gave Fox those reasons for a new suit in the last film. The change in suit design from BB to TDK was if anything a subtle evolution. Going to a nanofiber suit in the third film for similar reasons would be a huge jump.
If Wayne Industries was testing out these technologies already, why didn't Fox propose this suit of suit in the last film? Scientific breakthroughs don't happen overnight very often, especially when it comes to taking a new technology and making a workable product out of it. That takes years of testing and development. Thus, storywise, to me, a nanofiber/liquid armor, etc. batsuit would be too big of a jump.
Time delay since TDK would not explain it because why would Bruce still use the TDK exactly as first designed for much of the film?