All modern bullpups are ambi.
You're correct that they can be converted to left- or right-handed shooting, and that is an advantage over the M-16, which uses a little plastic ejection port guide to keep the brass away from your arm. But in the moment, I can't decide to shoot left- or right-handed. The Steyr's ejection port position is so close to the butt that your face would cover 2/3rds of it if you switched sides.
Some modern bullpups (Kel-Tech, Desert Tech MDR) eject forward, but that still doesn't solve the off-side ejection problem since the hot cartridge will bounce off whatever you're hiding behind. Hot brass sucks.
And I don't like the extra serving of spent gasses I get when shooting a bullpup.
P.S. In spite of some of the arguments surrounding the gun, I do have a small yearning for an MDR in 7.62.