Parallel Programming Development
Threading in Java definitely let us take a leap in threading programs. However it's still a hassle to write threading code especially for small algorithms. Like memory management of old, 30-50% becomes thread management, not the actual operations.
Iterating through a list I want to perform operations on each item in the list. I don't care what order it happens just that it happens quickly.
Another is the simple case of populating items into a bean in servlet such as struts. It doesn't matter what order the setters are called, just that all are.
If the run-time could speed these operations up with parallel runs that would really let us use this as a common language feature, not done by hand.