Part of the reason for the persistence of the Music vs Movies distinction is that very little music (especially popular music) has significant content below the low "E" on a bass guitar, which is around 40 hz. Maybe some portions of the kick drum spectrum. Maybe some outrageously low synthesizer notes. Otherwise there's just not much there. That's why the midbass modules mentioned above came about. Most of the visceral, chest-thumping impact that is associated with bass is in that region.
Anyway, tower speakers that adequately address the regions where music really resides tend to provide a coherent stereo soundstage for music. OTOH, subwoofers are better suited to capturing the low frequency effects so popular in movies. Thus the debate.
The real challenge is trying to build a single system that does both well (cause you're on a limited budget and your wife really isn't up for two separate rooms dedicated to music).
