Chord progressions are only hard to "pick out" in the sense of being able to name them by ear, but they're easy to notice in that they've happened; most of the time you just have to listen to the movement of the bass. The difference between C Maj and Gm isn't in the C and the G but in the Major and Minor. Minor keys have a flattened third (and often a flattened 6th and 7th, but the 3rd is the most important one). That flattened third is more unstable and thus lends itself better to drama, sadness, anxiety, etc., but even this major/minor difference is mostly noticed via chord changes. If a work in Cm hung around C, D, F, and G for a long time you wouldn't be able to tell if it was major or minor until it hit E-flat.OK, I see that; how important chord progression is, but for the untrained, chord progressions aren't easy to pick out either, whereas it's easier to hear an affective difference between a C Maj and a G Min symphony...isn't it?