I like the new name because it makes it clear that this is one of Google's apps, not a part of Android.
'Android Market' was confusing a lot of people. I've seen more than a few journalists thinking that, for example, the Amazon Kindle Fire is not a complete Android based system, because it does not ship with the Android Market. Some even called it a fork.
You're confusing Android with AOSP. "Android" is like "UNIX", it's more of an definition and API but not a specific product. Just like you have Solaris, IRIX, AIX, etc that are all UNIX because they satisfy the UNIX definitions; likewise AOSP, Sense, Blur etc are kinds of Android. I assume all known Android variants are derived from AOSP, but they don't have to be.
'Android Market' was confusing a lot of people. I've seen more than a few journalists thinking that, for example, the Amazon Kindle Fire is not a complete Android based system, because it does not ship with the Android Market. Some even called it a fork.