The sprites in the HD iOS ports, as well as the one in the picture above, seem to be based on the original illustrations the GBA sprites were made from. The Gyakuten Saiban artbook is full to the brim of those. If you have the book, check it out. If you don't, do a Google search for "The Art of Gyakuten Saiban".
They have thick outlines and strong colors because they needed to be downscaled to the GBA screen resolution, and have their color depth lowered quite significantly. It's not surprising they look off in full color and resolution.
Haha no. The sprites in the HD port are obvious trace overs of the original sprites. Very quick and cheap trace overs at that too.