Why do you think Bi-Wiring improves the sound ?

The only benefit of bi‐wiring is the increased speaker wire gauge equivalent you get running two sets of wires. Running a twin set of wire is equivalent to increasing the speaker wire guage by 3. For example, running two 14 guage wires is equivalent to running a single 11 guage wire. I have tried both routes and I would say If the cost is minimal, there is no harm in running a bi‐wire setup. I wouldn't go to the trouble of adding dual binding posts to a set of speakers though to accomplish this.

I bi-wire because the speakers are so designed & mfr encourages &  already had the wires from last setup. Adding a second pair of binding posts just to enable bi-wiring strikes me as nutty, as others have said. 
Nobody thinks bi-wiring is harmful, so if you've got the stuff already, go for it.

No! Bi-wiring does NOT improve the sound if your speaker gauge is sufficient to the situation. As mentioned doubling the gauge of the wire “could” help... but maybe not. It is probably the least expensive “Audiophile” tweak you can try but do try and let the rest of us know it it actually works for you! I’m willing to bet it will make no difference in the actual sound. 
** actual results may vary :-)

Not a fan. 

Some years back I had speakers that could be bi-wired or bi- amped. 
    The only advantage I see now from bi- wiring is you will already own the wire if you decide to Bi-amp,Which I eventually did do.If that isn't a future consideration, don't bother. The money is better spent on upstream components, not wire or speaker mods.