Don't worry, learning something is never a waste of time.
Anything you learn, and spend time to gain experience, will be replaced sooner or later; and the "later" cannot be more than a few years!
Long ago, people spent time to learn assembly language.
Some people used to know Fox Pro or Pascal very well.
Some more serious ones went after C and later C++.
Did they waste their time?!
When the new generation of object oriented languages (like Java) were introduced, nothing became obsolete.
Those who knew programming (in any language) well, just migrated their knowledge.
It's such experiences that makes a guy with 20 years of experience a powerful IT knowledge worker.
Plus, the "E" in the beginning of "EJB" speaks for itself!
If it's not suitable for enterprise development, why would they name it "Enterprise" bean?