Your sole reason for dismissing characters like Karai, Hun, Armaggon and Bishop for a new TMNT series is "They aren't characters I personally grew up with"? Sorry, but that's a classic case of "retro snobbery" (adapting the attitude of "The original is always superior, no matter what"). You're allowed to like or dislike whatever you choose to, but what makes it retro snobbery is dismissing any new characters or ideas simply because they're new and not what you're personally familiar with.
Keep in mind that the 1987 syndicated TMNT series is 20 years old now, so naturally, the viewers growing up now aren't going to have the same nostalgic fondness for the '87 series that you and others from your generation have, and since the new TMNT series will be airing on Nickelodeon, it's intended audience is going to be kids 1st and nostalgia buffs 2nd (if even that). Also, as previously stated, the 87 TMNT series was not the true, definitive version of Ninja Turtles. Furthermore, that series has been out of production for over a decade now. People seriously need to stop clinging to that 1 show.
I wouldn't mind it if the new TMNT series borrowed 1 or more elements from the syndicated show, but I would prefer if the new series tried to find it's own voice rather than just be a retread if the 1987 series, or even a continuation of the 2003 series.