I'm afraid I'd just be guessing about what may be happening in this case, but my experience is that prosecutors and investigators often prefer to have as much evidence as they can obtain, even when it may be redundant. I imagine they are motivated by a concern that one piece of evidence may be ruled inadmissible, or that the witness may not appear in court, or may be hopelessly impeached, etc. (Sometimes, perversely, it works to the defendant's advantage when his lawyer can seize upon even tiny discrepancies among multiple pieces of evidence of the same fact.)
So, just guessing, I'd say the delay is more likely due to the parties determining their strategies, and perhaps having informal meetings with the judge to mediate an agreed-upon process for reviewing the seized materials, perhaps even with briefs being solicited by the judge. I'm assuming that were there hearings on motions or other more formal proceedings they would have been publicly reported.
I think it less likely that the D.A. has decided that he doesn't need the materials obtained through the warrant, although I certainly appreciate your reasoning for a contrary decision.
My guesses could be ridiculously wrong if the case is being treated much less seriously than I think it is, but with the case receiving all this publicity I would think the judge and the parties are going to give this their full attention. There are, however, some local lawyers who have posted on these threads whose comments would be much more informed than mine.