It wouldn't have been commercially feasible. Cameron realized if he was going to spend that kind of money on the special effects, he was also going to have to draw a very wide audience. The fascination with the tragedy of the Titanic looks like it will never die -- see the Cameron IMAX "Ghosts of the Titanic" if one wants to see a documentary.
I have criticisms of the movie as well but I do see how Cameron solved the marketing problem and he himself stated, "I made a forty million dollar chick flick." I believe he was being glib as Robert Ballard who discovered the Titanic said he didn't mind the infused love story as Cameron had presented a very realistic and accurate reinactment of the event. The recreation of interior of the ship including even the plates and silverware in the dining room are really astounding. Probably one of the ten best set designs in all of cinema -- I visited some of it at Rosarita Beach in Mexico shortly after the wrap.
