I think the reason is that the Nolanverse costume is too hard to draw consistently. Seriously. Half the reason that artists draw characters who wear tights is that it saves the artists from having to draw a lot of details.
i would doubt that is the reason. or, if it
is the reason, it's shit. that's like saying there can't be a arc with more than 10 conversations because writers are too lazy. there are ways to simplify the nolan design to make it comic book friendly. i don't think it'd be all that more complex than many other suits in comics - it's essentially just drawing armor segments instead of muscle details; often even looking interchangeable. a quick tour through sites like deviant art, and you can see a number of fans have already done just that, like here:
either way, here's two more renders of the direction DC
is going:
again, there's a distinctly different look to each of these two, even just compared to one another. the top one looks very similar to the standard design, with some artistic tweaks (yellow symbol, invisible thong, darker tones). the second shot looks... odd. has a very bright, solid-color look to it. kind of like what they would design as "future batman" in the year 1963.
i find it to be too bold; the lighter colors, the logos, the clearly stylized design, etc. seems to be heading in the opposite direction from the nolan suit, whose every piece has a function.
