Only reason I can think of for the delay is if they are planning some 50th anniversary publicity stunt.
And why not announce the ones they have gone through?
Sadly, it was not just Doctor Who that was destroyed--BBC destroyed almost ALL of their archives. Tons of recorded shows from the 50s, 60s, and 70s were lost.
Marketing = stunts.
Film archivist Philip Morris of the Television International Enterprise Archive, who has spent decades travelling the world looking for… lets call it “insecure media”, has issued the following statement, regarding his believed involvement in the recovery of a large amount of missing Doctor Who episodes.
Much of it is is capitals.
A BRIEF STATEMENT .
T.I.E.A DOES NOT HOLD ANY MISSING EPISODES OF THE LONG RUNNING DR WHO SERIES. THE ORIGINAL VIDEO TAPES WERE WIPED SUBSEQUENT FILM COPIES WERE EITHER RETURNED TO THE BBC AND SENT TO LANDFILL ODD FRAGMENTS HAVE SURFACED TWO EPISODES ON 16MM FILM BUT THATS IT. THE PROGRAMMES IN QUESTION LIKE MANY OTHERS WERE DESTROYED AS THEY HAD NO FURTHER COMMERCIAL VALUE .THEY ARE NOT MISSING BUT DESTROYED THE END.I am sorry if this upsets some people but these are the facts.I have also become aware of the tracking of some of our clients shipments these are local cultural materials sent to us for migration to a modern format as the playback equipment in the country of origin no longer exists and as such is the best road to preserve international cultural heritage .I will be making no more statements on this subject.Philip MORRIS Executive director T.i.e.a
Rival archivist, Ian Levine, tweeted in response;
@JM_Watson Deeply sick, distressed, disheartend, all hopes dashed, all joy gone from the world. That’s it. DO NOT ASK ME TO SAY ANOTHER WORD
— Ian Levine (@IanLevine) June 20, 2013

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.