It was the lack of realism..since the bad writing, casting, sets, costumes, etc. lended to the lack of realism....it wasn't a lack of realism that made the late 90's batman movies suck, it was bad writing, casting and sets.
Batman's "tech" is militaristic in nature. We first saw him wear a black kevlar suit and use rapid climbing gear. Then he progressed to base jumping ability. Then he wanted a "visual" effect to induce fear in his enemies (the Batman look). Hell, his "tech" makes the old James Bond films and "Q" tech look like crackerjack box silliness.
I think the fundamental presentation of the origin of Batman and the anarchy terrorism/cleverly-crafted plots of The Joker is very "real world" realistic. Batman is not "super human" or "alien." He is a mortal man. How would someone actually be a Batman today? Well, someone would have to be rich and have access to the tech. A billionaire scion seems like a reasonable solution. So how does a Male Paris Hilton pull this off? By being a playboy douchebag by day...crime fighter by night...
Basically, it's grounded in reality. Same with the new Bond movies. No more "dapper gent" Bond avoiding death and destruction without a single hair out of place. The new Bond faces "real" threats and bleeds.
You can certainly hate the movie. I thought the "bat sonar" ability went too far. I didn't need Batman to have "sonar" ability. I don't need him to "become a bat." I like the symbol of fear.