Cdc, your comments are based in a rich misunderstanding of what it takes to make a good speaker. Fact is most single driver systems have worse timing errors than properly designed multi-element speakers.
Your history lesson also underestimates how much people love bass. For 99.999999999999999999% of the public anytime you get more bass....you get a bigger smile. Advertising had nothing to do with it.
Speaker designers are not obsessed with frequency extremes, the driver manufacturers are. In most cases better mid band performance leads to better bandwidth performance. Most good speaker design manufacturers are obsessed with either bass or midrange or simply obsessed.
Single driver speakers are not the answer, most are inferior for the very reasons you find flaws in multi-element designs. Exactly how difficult is it to perfect one driver to the point where it is demonstably superior to multi-way systems? You would think price advantages and limited R&D would make this style of speaker very popular. To build a Fostex in a box, you call madisound, cut some wood and you have a speaker. I'm not sure it requires any math?
BUT despite inherent market advantages, overcoming the obstacles seems to be very difficult, as this proven year after year. As single driver system remain only viable to fringy audiophile types who don't listen to powerful large scale or popular music.
A good example of the point I'm trying to make;
Cain & Cain Abby versus a Blue Sky System One? Both $1500, ones modern AM radio the others the real deal.
Guess where my money's going....with the ring radiator...
Best Regards