Zyuden Sentai Kyoryuger chief producer Takahito Ohmori finally explains to us why there is no KyoryuYellow in his show.
The last time Super Sentai had a male Yellow was in Mahou Sentai Magiranger with Tsubasa Ozu aka MagiYellow. The next hero of the Kyoryugers is something sort of close to yellow as the next addition of the team will go with gold.
Source: Henshin Justice
This is actually not the first time a team is without a Yellow member, J.A.K.Q, Battle Fever J and Dengeki Sentai Changeman never had a Yellow member. When it was decided that the Kyoryuger's would be required to defeat a dinosaur in order to be able to transform, we wanted the characters to be absurdly strong.
In order to show this, we chose to have more male characters over female characters. Seeing how modern Yellows have been female, we couldn’t have a male Yellow. If the Yellow was a male, the kids would probably think is feminine and we wanted to avoid that.
The last time Super Sentai had a male Yellow was in Mahou Sentai Magiranger with Tsubasa Ozu aka MagiYellow. The next hero of the Kyoryugers is something sort of close to yellow as the next addition of the team will go with gold.
Source: Henshin Justice