If they know it all, what's the point of hiring creative teams to make the shows? Some ideas only develop once the episode is in the can. I highly doubt every single idea for AGE is set in stone right now.
The show was first planned as a video game but Bandai/Sunrise liked it so much that they did it as a proper show. The whole AGE Systems very existence is so Level 5 wouldn't have to add more than one Gundam to the show.
Since Bandai, much like Hasbro would want to have lead time with producing toys to match the airing of the show they would want to have an idea what to expect. Bandai is also evil. They can very well get people to buy variations on the same design with newer features and accessories.
So in the end they probably win anyway.
Buy yeah. I could imagine waiting a few months until the power and speed variation limbs appeared and made a variable MG. Buying the same expensive items with new limbs feels a bit...
I'm aware of all that. However, we know fully well that things can change between even initial announcements mid-run. Perfect example- Anew in 00 was announced with character art which made her look shifty, since she was going to openly be a spy competing with Lyle. Then the sponsors insisted on a doomed romance plot, so this got shifted into her being an unwitting pawn for Ribbons. Even more importantly for mecha, things can change based on viewer response. Buster ain't selling? Let's stick Dearka on Archangel.
Whilst a vast majority of AGE concept is likely already pencilled in, there are always things that will change and new fun ideas that will only be hit upon whilst getting close to that episode. To give a direct example- which would you rather have? The clunky 1994 Master Gundam with barely any articulation or gimmicks or the 2011 HG with the cloak, Foonie and even a cloth wielding Master Asia? That's the kind of iconic nature I'd expect to see. Sometimes you need some breathing room to truley grasp what are the strengths of something.