You just might be surprised at what you're missing, in any case won't know until you've tried. Most are agreed this more than about filling in missing freq. This as much about improved sound staging through the cues offered by those lower freq that are either missing in action altogether or rolled off in main speakers. I'm getting nearly flat freq response down to 33hz in my room at listening position, subs not doing a lot here, but the added low freq cues greatly improved sense of spaciousness, could never go back to no subs.
And yes, I agree it may be hard to provide a coherent presentation when adding subs, I tired for years and absolutely could not achieve the kind of coherence I was seeking. I was and am extremely sensitive to coherence to the point I had to quit three way speakers for two way and single drivers for nearly a decade. Going back to three ways via present Khorns, took me years of listening and mods to bring these up to my requirements. Adding a pair of REL's really completed the picture, with careful setup I've been able to achieve wonderful coherence.
By the way there is nothing 'artificial' in adding subs. Subs are simply reproducing freq info contained on recordings, attaining flatter freq response and hearing those cues which improve sound staging is simply exposing what's contained within any particular recording.