I agree and why are so many prospects skipping the 3 cone & shuttle? -

I agree.

It would be much better if they put some DBs on the receivers.

The 3 cone and shuttle can point out quickness/ability to move the feet.
For the most part, and depending on position, guys who have "slow" 3 cone or shuttle times can't play at the NFL level.

Maybe they skip these 2 drills because they know they will run slow times?