I ported a Groovy/Grails app to Java/SpringMVC once.
My technical motivations were more about moving away from Hibernate. Arguably there were plenty of reasons for leaving it as it was, though -- if I had known enough to be able to solve certain data access complexities back then, Grails was in many ways a better fit for the problem. The experience in a (more-or-less) functional language wouldn't have hurt any either.
The business motivation was simple: Java/SpringMVC programmers are (or were then) far more plentiful, so adding/replacing tech resources was made much simpler.
My technical motivations were more about moving away from Hibernate. Arguably there were plenty of reasons for leaving it as it was, though -- if I had known enough to be able to solve certain data access complexities back then, Grails was in many ways a better fit for the problem. The experience in a (more-or-less) functional language wouldn't have hurt any either.
The business motivation was simple: Java/SpringMVC programmers are (or were then) far more plentiful, so adding/replacing tech resources was made much simpler.