You're right. Here are 10 sets of 15d2-12, where the average is 10.5 and the standard deviation is 1.94. (That's tight!) This is comparable to the Classic (3d6) method where the average is 10.5 and the standard deviation is 2.96.
(10, 13, 11, 7, 10, 8) = Unevaluatable.
(10, 10, 10, 12, 9, 9) =...