The trend in Android has been, up to now, in the right direction.
For example, the Android Open Source Project originally did not have a development platform build target or reference hardware. Now it does. That means you can take the entire Android Open Source Project and built it and run it, instead of having to "root" a commercial device and port Android to that device before you can start playing with Android on real hardware.
It is in Google's interest to make Android progressively easier to port because Google wants faster and more-consistent updates to Android across all the OEMs using Android. A vibrant and useful AOSP is important to that goal.
Moreover, when faced with a competitor using the Android Open Source Project to build a competing platform and support a competing ecosystem, Google did nothing to thwart AOSP, or to make it harder for Amazon to use AOSP.
Android is partly-open because Google uses a suite of applications and services that are not open source to create commercial Android products with the Google Logo, and OEMs and carriers add their own software to products. There may be room in the market for a more-open mobile OS that isn't tied to big e-commerce ecosystems. Tizen might be one such system, and Jolla might bring Meego back. If those systems prove to be more open, and under less pressure to provide exclusivity to their sponsors, they could turn out to provide truly open, hackable communications devices.
Open communications devices, with open hardware and software, are important because they would enable communications privacy, among other qualities.