Apparently, Google made this step to prevent fragmentation of the ecosystem. What are they going to do next? This situation is far from perfect for software freedom. Developing Android Apps in freedom is only possible as soon as the Replicant developers catch up. Looks like Android stops being a Free Software friendly platform.
At question are these nuggets in Google’s license agreement for the Android SDK (emphasis mine):
3.3 You may not use the SDK for any purpose not expressly permitted by this License Agreement. Except to the extent required by applicable third party licenses, you may not: (a) copy (except for backup purposes), modify, adapt, redistribute, decompile, reverse engineer, disassemble, or create derivative works of the SDK or any part of the SDK; or (b) load any part of the SDK onto a mobile handset or any other hardware device except a personal computer, combine any part of the SDK with other software, or distribute any software or device incorporating a part of the SDK.
3.4 You agree that you will not take any actions that may cause or result in the fragmentation of Android, including but not limited to distributing, participating in the creation of, or promoting in any way a software development kit derived from the SDK.