"Can't we just make an easy installer for Sun JDK?" "No, we're just going to take this opportunity to make our own open source project better."
This sort of crap is why Linux is NOT ready for prime time.
The problem here is not GNU/Linux, but Oracle playing politics (again). The result is that they will continue to alienate developers, while their cash cow won't suffer in the short term (hackers aren't responsible for the majority of their business, business-type decision makers are). The decision to focus on an open alternative instead of working around Oracle's antics is what makes GNU/Linux what it is. GNU/Linux isn't just a practical piece of software, but also an idea. That being said, focussing developer time on the OpenJDK seems like a pragmatic move from a practical point of view as well, because licensing reasons are not something you can just ignore when convenient (without exposing your users to a possible lawsuit from Oracle).
And that is why it is the preferred one! For enterprise stuff you have to have the "more polished" one.
For example, I work on browser-hosted user interfaces that sometimes rely on Java applets. I don't know why an applet frequently doesn't work with IcedTea. All I hear back via customers-of-clients is "Your interface doesn't work on Linux".
The advice to uninstall IcedTea and replace it with Sun's (OK, Oracle's) version is now as routine to our client's support people as telling someone with Windows troubles to reboot was a few years ago. That answer has a 100% success rate with these "bugs" so far, so I don't suppose those support staff are going to change their policy any time soon.
As a software developer, I appreciate that this is not at all helpful to those working on OpenJDK/IcedTea. However, as a guy whose rent is paid by what he earns from his clients, I can't recommend that anyone use IcedTea for anything until its well-deserved (in our experience) reputation for poor reliability is addressed.
Actually, you need the one built better, with better and longer term support. There is a lot of enterprisey stuff running on Java 1.2 out there.
And that's what they fear the most.
If you are interested in such issues, you are probably aware that Oracle has made the openjdk-7 the base target development of the JVM. Proprietary versions (sun-java7 is you will) are based on the free version. This is the opposite of the current version (6).
If we do not encourage users to switch to the Openjdk, bugs won't be fixed in the 6 or 7 for a while.
Seems like the same thought process at work that brought us cruft like the Unity UI in 11.04, then forced it on users as default, instead of just offering it as a new, less-stable alternative.