Sigh. The myth continues.
-Dallas made official trade offers of a second round pick in one case and a first round pick in another in an attempt to invest at safety. Had the other teams said yes, boom, there is your first or second round pick investment. Teams don't get to do every move they'd like to make, and Dallas has clearly been willing to invest in S.
-No, Byron Jones was not just a CB as a rookie. Don't know where that came from. He was used in a flexible rotational role that saw snaps at both CB and FS, and then even though CB is more valuable than S Dallas slotted Jones in at FS after year one. Admit it or not, that was a first round pick investment with a mind to upgrade FS, period.
-The front office has spoken in the past how they see value at safety: coverage. It doesn't value BOX safeties, to be specific, but that is far from limited to just Dallas. But if you ask scouts over the past decade, the rep is that reliable/projectable coverage safeties are not in great supply in the draft. Most of the most talented safeties are box guys, and the coverage guys often have major warts.

The Cowboys have been very interested in investing in this position that is not one of the core ones. But it's a targeted interest - wisely, the team has not forced an investment for the sake of doing any one, even with a prospect it doesn't believe in. Teams don't get to load up like the LA Dodgers or NY Yankees in baseball thanks to balanced, limited resources, and it's unwise to declare a total lack of interest or value in a position simply because of a lack of actual investments. As we've seen with the Cowboys, they have made some investments and tried others - the interest is there clear as day, unless one just blindly embraces media narratives that gets repeated often.