Lame. From the interview I read, JMS was inspired by Trinity from The Matrix. So when "updating" the most iconic female superhero in the world, he decided to mold her after a generic badass chick from an 11 year old movie that was the first part of a trilogy that nobody even talks about anymore since the third part bombed in 2003. A movie that based its aesthetics on outdated late-90s "goth" style.
I'll admit that I'm a "traditionalist" when it comes to superheroes; I like the iconic looks and I'm opposed to changing things around. But if they do change a look, I'm OK with it if they retain the core features of the costume and just tweak things around a bit. For example, that Xena skirt and uparmored breastplate look that they've gone with occasionally is something that I don't have a problem with.
This costume is just plain and generic. Without closely examining the details, it could easily pass for the jacket, pants, and tank top that any random woman on the street could be wearing. And I don't buy into the "it's more practical" argument either. Practical wardrobes goes out the door for a character like Wonder Woman, who can block bullets, get slammed through concrete, and take Superman punches. She's basically the female Superman. Does anyone talk about how impractical Superman's colorful cape and underwear-on-the-outside is?
JMS also argues that WW hasn't really changed her look in nearly 70 years. First of all, neither has Batman and Superman. Second of all, WW, like the other those other two icons, HAS updated her look. The Eagle was replaced with a "W" emblem, the laced-up red shoes have been replaced with sleeker boots, and the knee-length skirt has changed into a much shorter bottom. All nice little aesthetic tweaks, while retaining the color and visual identity of the character.
I only speak for myself, but I think part of the appeal of superheroes is that they wear colorful, visually striking costumes that make them unique. It's somewhat "cool" that a character can be so confident and independent that they can pull off such a gaudy costume. The bright colors also make them symbols, instead of mixing them in like this plain black leather outfit. Once again, WW is the female Superman. She's not some street-level vigilante.
This change has actually made it into the mainstream news, like CNN and Fox News. From a brief look at the comments posted there, it seems like most people don't like this change. I think it's a safe bet that this will be another failed revamp, and that within a year or two WW will be back in her iconic outfit. If you have such a well-recognized symbol, then the last thing you should be doing is to go away from it.
