This is being posted separate from my other post for search clarity. The same team that is questioning server vs. client, is asking how these interceptors are better than simply inhibiting input by the client for the duration of the submit. Are these interceptors falling off in popularity? Like plug-ins, it would be valuable to see what the usage numbers are for these features in terms of heuristics surrounding mainstream patterns today. Also, it might help to reduce the size of Struts/2 where "dead features" could be removed.
While having a dozen ways to do any one thing is possible, it doesn't always make things better. With lightweight being the name of the game, perhaps it's time to do a little pruning.