Loudspeakers have we really made that much progress since the 1930s?

As I opined here earlier, technology has advanced the performance of home audio gear greatly over the years.  The Shearer system that the OP mentioned is not a home audio system but an enormous thing designed for theaters and movie houses; it is totally impractical for normal home use.  The Western Electric systems of the day were essentially cost-is-no-object designs that were too expensive for even the theaters to own and were mostly leased out.  They were built when labor was relatively cheap and so it was possible to build handmade items in somewhat smaller production runs.  Home audio profited greatly from technological advances that allowed for much smaller speakers that could be manufactured on more capital-intensive production line basis.  The sound of home audio was completely different from that of the large theater systems, and over time that sound evolved to where we are now--a different aesthetic from those old horn systems.

I am certain modern designers could build systems that sound like those old school systems, and using modern materials and science, provide superior performance in the areas those old designs are lacking.  For the most part, they don't because the mass market has no exposure to that sound and so there is not much demand.  There are modern builders who cater to this niche market, but, they can only build on a small scale and cost, particularly labor, is extremely high so the stuff is EXPENSIVE (e.g., Goto).

Atmasphere is, in my opinion, correct that these vintage systems cannot deliver the kind of deep bass that modern systems deliver.  Even the massive Shearers and Western based systems do not have much in the way of punchy, deep bass.  The light paper cones with low-compliance suspensions that don't allow the cones to move in and out very far are not capable in that respect.  But, aside from that, they deliver a VERY special kind of sound.  If that is your particular taste, there are not many modern alternatives (and certainly not many reasonably-priced one), so it is mostly an academic exercise saying that modern designs are, or are not, superior.  The Classic Audio Reproductions field coil speakers certainly do deliver the incredible dynamics and clarity of the old school systems, and I will take Atmasphere's word that they deliver much lower distortion, but, I think they are voiced like modern systems and so they are not really "replacements" for such systems.

Mercedes produced a vehicle in 1938 that produced 736 hp and ran speeds of 268 mph.  That proves cars have not improved..

In 1964 the SR71 was produced, this plane set the absolute speed record on the planet in the mid 70's.... so, I guess planes have not improved.

Did the SR71 have cloaking capabilities?  Klingons?  Hmmm

These analogies are the same... great stuff was introduced a long time ago,  but the improvements have been massive. 

Everything that we have had to be invented at some point... Show me anything like a Magico... Shoot,  show me a Bose! 

Point is well made that there haven't been many New INVENTIONS,  but the improvements have been astronomical! 

So,  patent a Microwave that plays incredible music..... Never mind, that's just for fat guys.