If a cable running inside a speaker cabinet, passive crossover coils not included, is all of one to three feet long, and in some cases only a few inches long, the resistance over that distance, assuming the cable is in good shape and properly connected, would be almost immeasurably low. Over a very short run with negligible resistance at audible frequencies, no engineer is going to have a concern about skin effect or reduction of damping or who knows what else one might worry about. I think that in the manufacturing process, if the wire has acceptable performance characteristics for an 8-inch run, designers become more concerned with ease of working with the wire during construction, durability over time, etc.

There are probably pages and pages that could be written to explain engineering and electrical property issues that would speak to the many reasons why not having any reactive impedance (coil/capacitor) networks between an amplifier and a corresponding loudspeaker driver is advantageous. Certainly some passive crossover networks are designed to do more than simply divide frequencies, so if one were to remove the passive crossover network and go with a truly bi-amped or tri-amped situation, one would have to know if the active crossover network prior to the amplification needed to do more than be a simple frequency-dividing crossover. But assuming that an active crossover can perform the tasks that the passive crossover accomplished, going with an active crossover and an amplifier channel directly connected each driver will almost always result in some very noticeable positive differences.

Almost without exception, in all the professional sound-reinforcement situations I have personally seen, there is, at a minimum, active bi-amping. I cannot say that I have seen (or heard) an apples-to-apples comparison where the same system was operating while switching between the single-amp, passive crossover method and a multiple-amp, active crossover method. However I can say that the systems where the direct connection between amp and loudspeaker was possible, even at similar listening levels, the ‘control’ the amp had over the speaker driver gave the bass greater ‘definition and authority’ as well as allowing the treble more ‘clarity.’ Most production companies I have worked with would not buy double the number of amps and cable and increase their costs unless there was an obviously noticeable improvement for doing so.