Yeah, it could have been fluff based, but I'm really not sure.
IMO though, speaking from experience, the -2 to hit and cluster together is an ob combo, at least for clan tech. It just makes the ultimate crit seeker. If is tech was all that was to be considered, where the mpl really only has two hexes where it outdoes the standard ml, it wouldn't be too bad. Maybe it could work for both if you where rolling the damage on the cluster table as well though, but back then the cluster table was definitely smaller and we where just using base damage in clusters.