[zdragnar]

I think part of the reason is just the visual factor- TV screens don't do a particularly good job of showing off solid colored blades compared to how they look in person.

On top of that, I believe it is easier to run into problems with delamination, or that a small flaw can more easily be a larger problem.

If anything, it seems like an added challenge to demonstrate that you can do it, as a way to distinguish the blade in the final judging if it performed similarly to the others.

Ultimately, though, it's still just showmanship and not an actual indication of the quality of the blade itself. It's a TV show, after all.