mew , we all lived the Java/JEE nightmare , and pragmatic programmers got us out of that mess, with no desire to go back to that stuff. I'll take ruby/active record flaws over the "bloated and unecessary entreprise pattern" code anytime.
It might not be wise to go back to bloated JEE. However, it would certainly be unwise to leave the knowledge behind. People working in Rails and Django applications need to learn those important lessons. It can save them from a lot of common pitfalls. I have seen people using a large number of servers for Rails applications while similar load is handled by less half their number of servers using Java.
How did J2EE become a night mare. It was pretty clear to me that you put your business logic in session beans, and they manipulated entity beans along the way.