Looking at the post, reason number one is "Your application already works on 5.0". Then I see it, a subpoint under this section...
New Look and Feel
The Java platform already contains a pluggable Look-and-Feel framework. The addition of the new Ocean Look-and-Feel enables cross-platform applications to switch between Ocean or the native operating system's look-and-feel, without the need to rebuild or recompile them.
The answer to all my problems has been found. Ocean will make the move to 5.0 painless, save time, and get me a beer out of the fridge.