When/why was the list of Kodokan Judo throws and ground techniques recently expanded?

Question

Toshiro Daigo's book Kodokan Judo Throwing Techniques published by Kodanasha International, Tokyo 2005 lists 67 throwing techniques. As Daigo is the chief instructor at the Kodokan, I took this as the authoritative source on throw classification. The Kodokan website now lists 68 throwing techniques. The changes appear to be:

• +Obi-tori-gaeshi was added
• -daki age was removed
• +kouchi makikomi was added

This is the first change I am aware of in my lifetime. Out of curiosity, what prompted this set of changes?

Answer 1

As of when, this can be found here: April 1st, 2017 (and it's not been an April's fool!):

The Kodokan has used official technique names consisting of 67 Nage-waza and 29 Katame-waza in the past.

After giving further consideration, two techniques of Nage-waza, Obi-tori-gaeshi (Te-waza) and Kouchi-maki-komi (Yoko-sutemi-waza), and three Osaekomi techniques of Katame-waza, Ushiro-kesa-gatame, Uki-gatame and Ura-gatame were added to the existing official technique names as of April 1, 2017. One technique, Daki-age (Koshi-waza) was deleted from Nage-waza.

Accordingly, 100 technique names consisting of 68 Nage-waza and 32 Katame-waza are recognized as official technique names.

As of why, there is not much more to be found than the opaque "considerations" mentioned in the news itself.

Addendum: This reddit thread discusses (and I think rightfully so) at least regarding Obi-tori-gaeshi and Ko-uchi-maki-komi that it is basically the recognition of distinct techniques successful in sports Judo (Obi-tori-gaeshi is basically a Khabarelli) as such.

Answer 2

Reasons for changes

To expand on Philip's answer, the Japanese report from the Kodokan states the change is in response to the increased prevalence of these techniques in the previous 3 years:

平成26（2014）年から多彩化を続ける技術に対応するため、講道館技研究部で、技名称の再検討を行ってきた。

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In order to respond to the ever-diversifying techniques from 2014, the Kodokan's Waza Research Department has re-examined its technique classification.

This is similar to their reasoning for historically adding the shin-meishō-no-waza:

講道館では、これら48本の投技名称を正式のものとしてきたが、ここにある技法以外の技が用いられるようになった状況を鑑み、新たな技名称の制定について慎重に検討を重ね

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The Kodokan made these 48 nage-waza names official, but in view of the situation where techniques other than the ones in this category have been used, the establishment of new technique names has been carefully examined...

The specific recognition of the katame-waza was probably in part motivated by the IJF's recognition of ura-gatame in 2013 as a valid osaekomi-waza for point scoring.