I ninja-edited my post. Previously the EV for uniform guessing was zero, because the points value for all the answers (1, -.25, -.25, -.25, -.25) summed to 0. Now the EV is positive because they got rid of the -.25 penalty.

To make things more complicated: if you were gunning for a high score in the old system, it was even more important to guess, because your partial points could get rounded up.