Shesh, you guys make it sound as though Sega is screwing over its dev teams! I'm sure they didn't mindlessly move people from one studio to another! I'm sure the developers had a say in how the groups were matched up, and to me the whole thing seems very logical if you look at the games each team has made.
First off, I can guaruntee you Sonic Team's U.S. division, which made Sonic Adventure 2 and is now working on Sonic Heroes, will remain virtually untouched. Secondly, larger development teams can work on multiple projects at once. Keep this in mind for the complete mergers!
You're right: keeping AM-2 intact seems a bit strange. It has always been an oddball Sega team, with its Virtua Fighter and Shenmue... I suspect a lot of Yu Suzuki's new team comes from AM-2.