My problem with windwall (against Nami

Yasuos wind wall is annoying, especially when he blocks your ult. I realize that's what its supposed to do, block incoming stuff. But right now, my only problem is they way wind wall works against Nami's ultimate. Why should wind wall block Nami's entire ult, if it only touches a small portion of it? I think it would be fair to make it so, for example, if wind wall blocks half the wave, instead of making the entire wave disappear, make the other half of the wave keep traveling, because wind wall didn't block that part of it.