I admit that really surprises me, and it makes me wonder if they’re bizarrely holding onto it as a surprise reveal. G has been reasonably popular in Japan and well loved in the west. It makes no business sense to leave G out entirely. Seems to me like you toss in Shining, anything Master Asia piloted, plus maybe Nobel Gundam if you’re feeling a bit silly, include a few fan favorites as Strikers and boom, you’ve sold some more copies.
Granted, at this point I’m personally happy with the roster as it is but I’m not hard to please. The Nemo alone goes a long way to winning me over, and the only things I’d really like to see at this point are playable ReZEL Commander (it’s a Striker, but unknown if also playable), Rick Dias (also a Striker, unknown playability), Schuzrum Dias (no sign of it), M1 Astray (striker so far), and its successor in the Murasame (no sign of it yet?).
Still, I could have great fun with the Nemo, Hyaku Shiki, Gundam Mk. II, Jagd Doga, and Char’s Zaku II Commander as it is; that’s legitimately a fun roster to me so my realistic hope is they fill in slots that make others happier.