Why the fascination with subwoofers?

It's affordable to add a sub to your system, versus buying full range.  You do not have to spend big bucks to get a sub now.  What full range speakers are you referring too?  It all depends on your mains, if your speakers are flat down to 20 hertz, you really don't need a sub, unless you listen to some rap or other bass heavy tracks.  If you want to get low, you need a sub.

My system sounded much better after removing the subwoofers.  A friend of mine asked what subwoofer should he be looking at to replace a dying one and I told him that his speakers had dual 8" woofers and his room was rather smallish so he absolutely didn't need a subwoofer.  He took it out, listened for a while, and realized he just saved a few thousand dollars.

Many people today like loud rock music.  Live, these songs are aided by towers of lousy speakers driven by even worse amplifiers that the move so much air the stadium shakes. 

People who have grown up with this thumping noise and gut-punching "music" want to reproduce that in their home and car systems; subs help IF they are efficient enough to work with their internal amp (powered) or your external amp--needs to be rather powerful unless you have Cerwin-Vega or other very efficient bass-heavy speakers.

Orchestral music that features actual music or sounds and harmonics (cannons, for example??) that enter the lower frequencies that humans can hear also require speakers that reproduce those frequencies accurately.

Systems that incorporate large bass cabs, like the old Mark Levinson HQD system, which used 24" Hartley speakers in huge cabs, actually CAN reproduce those frequencies given enough CLEAN amplification and the proper crossovers, etc.  Such systems not only give the listener the "live" experience, but also provide (as accurately as possible in a reproducing system) the live orchestral experience.

Finally, film buffs who have exotic home theater systems use them to reproduce the artificially-enhanced soundtrack of their fav films showing buildings blowing up--not really in the 20HZ range, but ENHANCED is the key item here--and other loud, gut-punching sounds that are really in the lower mid-range, but who's quibbling when your room is shaking and your stomach is pounding?  

Soon, we will have holographic films where the action will take place IN YOUR ROOM, or seem to, anyway.  Sound in those cases has to envelop the viewer/listener, and the love of the gut-punch or explosion at 120db is what people seem to want.  Well, until their ENT doctor gets ahold of their hearing tests, anyway...

Cheeers!

IT's probably true subwoofers get a bad rap with audiophiles because in many cases they are set up in a manner that adds too much bass which can also obscure the higher frequencies.  

But like anything else, its just a matter of doing it right, using the right sub set up the right way.    

The best setups do all frequencies in music one might hear well, generally accepted as being from 20hz to 20000hz.   Older ears will lose their ability to hear the higher frequencies over time  but not the lower.