Great thread, great games.
Like you I was disappointed with the omissions in the sequel to All-Stars Racing, especially regarding characters. With both games combined rosters in one there'd be a much better selection and representation but those holes are glaring in each of them. I liked that Transformed brought back Gilius and NiGHTS, but then again it took away the likes of Jacky & Akira, Billy Hatcher, and Zobio & Zobiko, who I ended up using a lot.
The games were really frustrating and difficult to play in parts but overall enjoying and great with friends. I completed the first one on X360 completely (I forgot about that annoying Achievement glitch, thanks for reminding me...), and have the sequel on 360 and PC. Didn't care for the guest characters really, it would be great to see Mario appear next time and have Sonic appear in the next MK game too.
The music for me, was ok, but somewhat generic even though it had its own sound, it wasn't something I'd listen to again or want to bop to on a whim. The realcrime in Transformed was the removal of "Samba de Janeiro" but I'd imagine that was from not getting the rights to it, but that's my tuuune and made me play on the Samba de Amigo stage all the time with my friends. Some of the House of the Dead and JSR music wasn't as good in Transformed either. It would be great to see a Space Channel 5 stage next time around, all the removed characters returning, and some sort of Streets of Rage additions.