It's Simple

Ieales, Let’s imagine 0.1 ohm (both ways) cable connected to 8 ohm speaker that has lowest impedance of 4 ohm. At 4 ohm we have divider of about 1/40 equal to -32dB while at 8 ohm we have 1/80= -38dB. Do you think that 6dB difference in audible area won’t make any difference?

You might be right that cable R can be ignored only for the purpose of damping factor, since there is always speaker’s own impedance in series with back EMF force (and 2/3 of it is resistive), but one can argue that capacitance and inductance are not that important either. Almarg pointed out that speaker, having inductive character most of the time, has very high impedance at high frequencies (where cable inductive reactance can go as high as 1 ohm) while capacitance plays very small role because of low output impedance. As for the skin effect, that you mentioned - it starts at about gauge 18 with copper at 20kHz. Our ears are not very sensitive to volume change but are very sensitive to frequency smear. When you change loudness by 1 dB nobody will be able to detect it but when you adjust treble by +1dB you can detect it easily. In order to provide low resistance without frequency smearing companies split wires into multiple strands. It won’t help much as long as the strands are in magnetic field of each other (skin effect exists). To improve it cable designers place conductors on hollow tube (or flat cable pattern) reducing magnetic field to one that comes only from neighboring wires.

Proximity Effect, Skin Effect, Purity, Metal, Plating, Insulation Dielectric, Fatigue, etc.

yes, these and others are probably as important as LRC, especially R, although changing R changes the reactive LRC. 

definitely not as simple as just LRC especially when, as indicated, 75mm of wire, strategically placed, can completely change the sound by an enormous amount. 

once someone works it all out then it is probably simple - until then - although building a bridge is usually not simple yet we see them everywhere.  Some bridges can be very simple but do they really do the job, in some cases sufficiently so and in other cases not so... perhaps there are too many variables, and too many assumptions, to allow over simplification, although like bridges some simplification is possible and sufficient.

Let us not forget directionality and cryogenics. You know, if you want to compete with the big boys.

@kijanki

I’m not going to correct all your errors, but this the level math:

Assuming 0.02Ω in each cable lead [12’ of Belden 1311A or almost any equivalent gauge cable] with a 1V drive at the amplifier terminal:
4Ω: 4 / (2 x 0.02) = 0.990V across the speaker
8Ω: 8 / (2 x 0.02) = 0.995V across the speaker
db: 20 * log ( 0.990 / 0.995 ) = -0.043db

Doubling the lead resistance, +3 AWG numbers, only has 0.086db loss.

On a speaker with an impedance that varies from 4 to 16Ω, the total delta across the 20-20k is 0.13db or ±0.065db which is extremely difficult to hear on a dynamic signal.