They used to hire a fan. His name was Ichikawa Hirofumi. I don't think he decided on which toys were reissued -- because that depends on certain factors like:
a) What fans wanted. Remember the old reissues had those self-addressed survey cards that let you
nominate up to three suggestions per card of which toys you wanted reissued? Because I know most of the toys that my friends and I asked for
did get reissued.
b) What moulds were still available. A lot of fans would've asked for Mirage, but that mould is lost/destroyed so it's not possible.
c) What moulds are viable. e.g. Takara's always had the moulds for the Constructicons but never wanted to reissue them until the Encore reissue because there were so many KOs of Devastator out there they feared that a more expensive legit reissue couldn't compete.
What Ichikawa Hirofumi did have a direct input into was what colours to release for the eHobby exclusives. In fact, he wrote up all their tech spec profiles and names! It was his decision to make them based on their original Diaclone and Microman colours, or based on some obscure characters that only fans would appreciate (e.g. Hauler, Sunstorm etc.).

He also wrote the entire Story of Binaltech and all their profiles, plus a LOT of other stuff for Takara. It not only gave fans what they wanted, but also helped heal Takara-fan relations after the way Takara shafted Ichikawa (and fans in general) at BotCon Japan 2000.
As for chrome Bluestreak and gold chrome Jazz... yeah, they're weird. But they were lucky draw prizes given away as freebies. I don't expect much quality from freebies.
