Sometimes Hard to Drive Speakers are a Gimmick

As paralleling two woofers in a tower speaker with a mid and tweeter is very common, deciding the impedance of those woofers along with the crossover design will define the low ohm situation that will fine tune the sound.

If you mean, you’ll end up with a lower impedance than with just one, yes, absolutely, and this trade-off is well known, and expected, often resulting in 3-ish impedance in the mid bass.   I don’t consider this malicious so much as a trade-off.   Want lots of bass in a small footprint? This is one way to do it.  I do this myself with my bass cabinets.  Not what I’d call a designer out on. 

  The debate seems to be whether some caps & resistors in the crossover are there just to make the speaker sound different (preferably better) with "low ohm" capable amps to elevate the perceived value of the speaker and/or amp ? 

I don’t actually have a problem with well-designed impedance flattening circuits used to eliminate drover resonance peaks.  Yes, they take current but they should bring the overall impedance and dissipation down to no worse than the rest of the speaker.   Such a circuit that results in practically 1 Ohm loads, or worse, for no particular gain is not IMHO a well designed circuit.  Is it malicious, or meant to show off what a high power amp can do?  I’d have to put the designer under oath. 

The benign version of this circuit by the way is rarely used as the wattage dissipated and parts costs can be high. 

The Focal circuit I show you was NOT a case where impedance was flattened with clear benefit to anyone.  Half of it should be removed, and the rest I showed could be rethought yielding much better bass impedance. 

Another very typical impedance lowering circuit is a Zobel, which is used to help a filter circuit behave as intended.  I wrote about this here.  Again, perfectly acceptable space heater.  

@OP - With all due respect, there is a lot of dubious logic in your blog post:

"Many audiophiles unfortunately believe that a speaker that shows the difference between upstream components is more musical or easy to listen to.  They are not.  They just show differences better, but these buyers will prefer the speaker that is harder to drive, and then buy a bigger amplifier."

Re above - first there is a false premises argument. The first sentence is merely an unsupported conjecture. Then there is a syllogistic fallacy viz the alleged preference of audiophiles stated in the first premise leads them to prefer speakers that are harder to drive and consequently buy bigger amplifiers.

Sorry if it appears harsh but your argument is just nonsense.

I read your blog post, and from it I glean that you think some speakers have unnecessarily low impedance. Fair enough, though  I would imagine that the professional designers of the speakers might disagree with you. But as for the rest...

It's up to the engineer to watch the impedance curve of their design. Something designed for a big room will use more energy. But it can still have a reasonable impedance curve. Low watt amps make them sound indolent. 

Only commenting on your Zobel curcuit commentary eric; well done.  When I commissioned George Short (then owner/operator of Northcreek speakers/crossovers) to build me a couple of crossovers for our B&W Matrix 801 S2 speakers, I asked him to include switchable (i.e. in /out) Zobel circuits for the woofers as were provided by B&W in the factory crossovers (not switchable, always on).  Interestingly, the woofer Zobel curcuits were eliminated in the Series 3 Matrix 801, IMO one of several reasons why it falls short of the Series 2 version sonically.  In any case, as expected, the Northcreek crossovers dramatically improved the speakers’ sonics and equally as expected, so did the Northcreek Zobel circuits.  Eliminated the switches; Zobels always on.

I think the OPs premise is absurd. No designer worth mentioning adds complexity to a design to achieve a negative attribute.