Google has done this move to protect itself from fragmentation, says Bloomberg / Google.
Well, that’s a bit exaggerated:
1. Fragmentation means letting everybody hack and mod the Android OS until it looks and behaves cool enough to be sold (read “until it resambles iOS”).
2. Being able to hack and mod an OS means that OS is open.
Conclusion: “fragmentation” means “open”.
Now, Google says they are closing the OS to avoid fragmentation; this is “they are closing the OS in order to avoid letting it open”.