It really seemed like it could have been a no-brainer. Studios are making bank by re-releasing hits of previous decades. Jurassic Park, Titanic, Beauty and the Beast, Monster's Inc. I know those all got 3D upgrades but they still had 2D showings in most theaters.
They could have even pulled a "Raiders of the Lost Ark" and just released the 1987 version no frills in all its 2D glory.
I'm guessing they were hoping for a Batman Begins/TDK-esque blockbuster reboot of an old character but if they really thought they had a hit on their hands this would be a midsummer release, not spring. Should have just treated new audiences to the original masterpiece on the big screen.