I clearly see both sides of the argument.
Like you, I lean towards the Cowboys addressing defense early and often coming up in the draft. They could use an addition at every level of the defense.
But...
More than anything, though, the Cowboys
need to be right about Dak being the next Franchise QB of the Dallas Cowboys. That trumps everything. Because if he isn't that will set them back for years while they try to find their next most important player on the team. So, the emphasis on being Dak-friendly to a certain extent is understandable. For me, though, if that's the stance your taking, the friendliest thing they could do is give him more time in the pocket by fixing the offensive line. Beyond that, improve the defense so you can give him more opportunities to score as the defense shuts down the opposition on third down. Wide Receiver in this scheme just really isn't as important as I think most people tend to make it. If they can catch and simply be where ever they are supposed to be at the top of their route, that's all you really need to win with this team. Speed and run-after-the-catch ability are nice to have's...not have to have's like the aforementioned qualities.
And that's what I really think this WR shake-up is about. Romo most likely spoiled the current receivers because of his ability to read defenses and know where his guy's where going to be regardless if they ran a crisp route or not. Dak's not there yet, so rather than try to teach old dog's new tricks, they are bringing in new dogs who will from the outset recognize Dak as the unquestioned leader of their team and hopefully assist in his ascension to greatness...or at least, that's what I think they are thinking...