Why not acoustic suspension?

There are 2 critical components in an Acoustic Suspension speaker 1) a truely sealed box 2) a woofer that is essentially floppy and unable to operate correctly in free air.  The spider and suspension of an AS woofer are extremely compliant, and the woofer cone will essentially "ring" following the signal.  The woofer design requires the fixed volume of air in the cabinet to add a damping force to the woofer while in use.  The cabinet is fully sealed (non leaking), and the air compresses as the woofer receives signal.  The amount of air compression and force with which it pushes back to restore a pressure balance in the cabinet can be calculated, and then used to damp woofer motion and prevent ringing or distortion.  An AS woofer can reach very deep, with shockingly low amounts of distortion.  The offset is low efficiency, and a requirement for a lot of power to get the best from the woofers.  AS speakers are typically paired with higher powered amplifiers compared to a ported design.

Non AS designs include closed boxed, or infinate baffle designs- Bozak speakers are infinate baffle.  The box may be sealed, but the woofer will also work quite well in free air, and does not need the restorative force of the internal air volume to produce distortion free bass.

The LS3/5a box is lossy....while it appears sealed, some air does escape from the joints between sections of wood.

Ported designs are more efficient, so they can play louder with less power.  Ported designs can be made to deliver acceptable bass response (not as deep in general as AS designs), but in a smaller cabinet.   One can use off the shelf components instead of requireing custom designed drivers.  All of this translates to a manufacturing cost.

With the trends favoring vintage or vintage inspired designs, I am surprised that only KLH has introduced AS design speakers.  They have been well received, and by all accounts sound wonderful.

With the trends favoring vintage or vintage inspired designs, I am surprised that only KLH has introduced AS design speakers.

Guess Magico, ATC and YG have ceased to exist

About a year ago I made what I thought were homemade acoustic suspension speakers. Now I realize they are sealed box speakers. I really like the sound they produce and feel I did a pretty good job for a novice. 

One thing I had read was that acoustic suspension is in a well sealed cabinet but not perfectly sealed. A perfectly sealed box would build pressure as temperature rose so a little allowance for air passage is warranted.I think Henri Kloss had designed his woofers to allow some air to move through the outer cloth  material, flexing part of the driver. Reading that, I put a small 1/8" hole in the cabinet for pressure equalization given my drivers were a rubbery material which wouldn't allow any air passage. My tiny "vent" didn't seem to affect sound they produced. 

As I implied previously, though, a good closed box has superior fidelity to a goo ported box. Ported boxes(including passive radiators) are boom boxes compared to closed boxes assuming proper design.
 

That’s a misleading statement IME, especially regarding passive radiators. Some of the most articulate and defined bass I have heard came from ported, MLTLs, or passive radiator designs. I will say the average ported box does sound boomy relative to the average sealed box design, but like most things in audio, there are notable exceptions. It ultimately comes down to the competency of the design. 
 
 

I've had 9 or 10 pairs of speakers over the years. In the last 2 decades speakers lived in my space limited home office system where desktop/nearfield placement is mandatory. I found out the hard way that the 3 sealed/acoustic suspension designs simply sound better and interact less with the room than the 3 ported speakers. It's not even a close contest.

My current speakers are the vintage sealed KEF 103.2s, which are wonderful 2-ways (soft dome tweeter + 8" woofer). Two more recent sealed speakers that also worked beautifully here were the ATC SCM12 Pros (Their smallest studio monitor, a passive design) and the Aerial Acoustics 5Bs. 

I have a vintage pair of Boston Acoustics A40 2-ways (also sealed) in the living room. They sound great in a location that would cause real trouble with any ported speaker.

All in all, I'm a big fan of sealed/acoustic suspension designs. At least to my ears, the bass sounds more forceful, controlled and tuneful than any ported design's does, and I've had some good examples of those, too.