I've said this before, but I read somewhere that Shu Takumi's initial plan for the first Phoenix Wright game was for 1-2 to be the finale case of the game, but producers/editors told him to pick up the pace.
So GAA1 is what happens when he's established himself enough that no one gets to tell him what to do anymore, apparently.
(I actually don't know how I'd speed up GAA1 anyway - cases 1 and 3 are necessary, and 2 is mostly necessary as well, at least for Kazuma and the introduction of Susato and Sherlock), and I think G1-5 needs at least
one
normal case in Britain before it, but maybe that's not true and it could've worked as a case 4, with a real finale case as a case 5.)