Hotter pickups in general have more midrange than the lower output ones (and less highs). Simplified, this means that the mids distort more than the low end, which means that the low end stays cleaner and tighter. This is also what your typical tube screamer pedal does; it cuts the lows slightly and adds midrange.
But there are very crisp and tight sounding low output pickups too, like the Riff Raff. I'm actually leaning towards lower output pickups these days, because of the touch sensitiveness and the (with the right pickup) woody tone. I have a serious itch of ordering a VHII or a RR set for my (warm and middy sounding) PRS McCarty. It's just that the current Cold Sweat set in it sounds so damn good for hard rock and metal. Maybe I should just by another guitar

-Zaned