It's only scary if you assume that they wouldn't have addressed the WR position later on. You're correct in saying that it was a deep WR draft. They clearly had Watkins rated far ahead of the other receivers (or any position for that matter). Ebron, as their backup plan to Watkins, makes sense to me. He was a FAR better prospect than any other TE in that draft. Why take the 3rd best receiver in a draft when receivers 4-10 on their list were likely rated nearly as highly? They could have taken Ebron and still ended up with someone like Allen Robinson or Martavis Bryant.
Picking Watkins just speaks to how much higher they thought of him than everyone else.