From what I recall, there was a reason why we didn't get them. The reason given was rebuked by the community though.
If I recall correctly, the reason given was that more proper Primal glamours for the egis would obstruct too much of the view of the players, to which the community responded to this by saying that the Demi-Bahamut and Demi-Phoenix already have resize commands so players can choose to make them smaller. Then, there were some Youtube channels which covered a fan-made mod whereby the egis were replaced by their respective Primal models, and that actually received a very positive reception.
I wouldn't be surprised if, given the current state of the Eden raids reintroducing our player characters' own reimagined versions of the Primals, if 6.0 SMN didn't somehow try to reintroduce them into the actual job. We have yet to see Ifrit and Garuda reimagined, after all... and part of me sincerely hopes our reimagined version of King Moogle Mog is based on Madeen from FF9 :P I don't know for certain if egis are truly going away, since SMN and SCH are currently THE pet jobs (until Beastmaster is introduced, which would negate the need to remove the pet interface), but I guess we'll have to wait and see.
If DPS jobs ever got mounts like tanks, I would hope that we could sit on E4 Titan's shoulder while he rides his quadbike :3
