ncurses3 was removed in beta2 and replaced by ncurses4. Some old binaries (e.g. Legato Networker) from RH 5.x era still use ncurses3 libraries. I wouldn't see any harm including that in the distribution, even though it wouldn't be installed by default.
We don't ship 2 compat versions of the same library. Guess it's time to really obsolete some old stuff.