Of course bi-wiring can be better. The very first thing I ever tried with cables was to shot-gun, essentially run two sets of wire from the amp to the speakers. It seemed this could make no difference since according to the wire is wire brainiacs I had enough gauge and so another set cannot help, but it did. I always whenever possible try and listen and not take anyone's word for anything.
Of course once having proved something is better you still have the question, but is it better for the money? Clearly it was better, but not by much. The wire on the other hand now cost exactly twice as much.
In other words this is like everything else no magic bullet. Instead it is like nonoise said, bi-wire can be better than jumpers, but one good cable with jumpers can be unbelievably better than bi-wire.
One small yet very important detail no one ever seems to mention, the very fact your speakers is even capable of being bi-wired reflects a decision on the part of the manufacturer that you can never undo. Every connection no matter how good is a weakness. A speaker with extra terminals is a speaker designed from the get-go to be weak. Sorry, but it is just a fact. Like, there is a reason none of the really good pre-amps have tape loops and 15 inputs any more, all the really good ones are minimalist with only a few of anything. Because they all know that is money spent for no benefit to sound quality.
Anyway, what this means is that any speaker set up with terminals to be bi-wired cannot ever truly be compared any other way. Because it will always have those jumpers. Essentially what you wind up comparing is not the cables but the jumpers. There are probably about as many jumpers as there are cables. instead of being in a situation where you are able to compare speaker cables one against another and arrive at a solid conclusion you are now in a situation where you never can be sure, there are at least twice as many configurations (see above) and so you have added cost, signal degrading contacts, and expense in order to greatly complicate an otherwise relatively simple choice.
My hunch is the guys who like doing this simply like doing this. Which is fine. For those who haven't tried but are considering, good idea to go into it with your eyes open.
