As for speakers, sorry to be grinch, but there is no way a cone speaker (except possibly these woofers) in any cabinet made from any material sounds as accurate as speakers that don’t use cabinets regardless of the materials or design parameters. Do not take my word for it. Put speakers in cabs side-by-side with non-cab speakers and see for yourself, please.
Been there, done that. For example, the Stirling Broadcast LS3/6 sounds far more accurate and neutral than Magnepan 1.7is, and with more transparency. It’s no contest, those wide baffle monkey coffins are simply better speakers, but don’t take my word for it.
I was under the impression that the purpose of the cabinet was to add to the richness of the sound, versus just the speaker itself. Just as the body of violin or bass fiddle adds to the richness of the sound it produces. Is this not true?
Not true. The box is meant to load the woofer and prevent the speaker from acting as a dipole, which creates diffuse sound and excessive woofer excursion. Dipoles are typically less efficient than box speakers for a given diaphragm size. If what you guessed was true, speaker boxes would most often be made of thin tonewoods, which is obviously not the case. And no, it’s not due to expense. A thin mahogany box is fairly cheap to manufacture. One can get a brand new mahogany guitar for $200.
Most modern speaker manufacturers have a pretty good understanding of speaker physics, believe it or not. That so many here are questioning their use of boxes and MDF is baffling to me (no pun intended).