Question about Katarina's new W

Because it is not a skill shot

She is essentially dropping it where she is in "Preparation" (conveniently the name of the ability), but there is a delay before she is able to use it. Animating the ability to have her toss it up into the air is actually just a logical way to illustrate a delay.

Technically her Q is already a skill shot when it comes to the placement of her dagger.

The position at which the dagger lands is based on the rotational position, in respect to the first target hit, because the dagger will always land as close to a fixed distance on the opposite side of this target as possible.

Making the placement of her Preparation dagger into a skill shot as well would actually be unnecessarily complex.

That isn't to say that it couldn't be, .. but I just don't see any reason to do it, opposed to a reason for them not to.

For one, maintaining simplicity is actually a good thing because her mechanical skill requirement has increased significantly.

Also, making the dagger placement be elsewhere would actually increase her opportunity for mobility, which she has quite a bit of as it is.

Having it drop at her feet after a delay actually requires her to move away and return to that position.

This actually limits her mobility, and increases her enemy's opportunity for counterplay.