Drafting is always about a combination of need against value. The Jets tend to put emphasis on value early in the Draft. The front office is well aware of needs that exist at outside linebacker and safety. They just thought Muhammad Wilkerson and Kenrick Ellis were better than any players at those positions. The short term value of filling a hole was presumably deemed less important than potentially solidifying the defensive line for eight to ten years if those picks pan out.
The later you get into the Draft, the more greater the emphasis value takes. Most guys taken near the end of the Draft are either not good enough or not developed enough to start effectively in the NFL as rookies. The third day of the Draft is not a spot to fill needs. Anybody picked there has been passed on several times by every team for a reason. There are not many guys who start right away. There are some exceptions, but they are just that.
Bilal Powell is an example of this. I have stated that I am not his biggest fan. I do not think he will be a total bust. I think he will be ok. The Jets apparently love him, though, and think he can be an impact player. (And it should be noted that Mike Tannenbaum runs the team while I only write this blog for a reason.) They did not think a safety or outside linebacker in that spot would make as big of an impact.
Taking an outside linebacker for the sake of taking an outside linebacker would have been self-defeating. Just because a guy plays a certain position does not mean he will be a great or even good player at that position. Even if he becomes a good player, that might take years of development. Taking a player does not guarantee he will be an upgrade over what is already there.
There is a reason the Jets did not fill all of their needs in the Draft. I find it difficult to get on them over it.