Hi Jen! Good suggestion. It's something I'll look into doing next year.
I like to leave details of past events on view for awhile after they are hosted as I still hear from people interested in doing the workshops etc, then I can gather names for the next time the event is hosted. Plus I like giving people a chance to comment on anything they may have attended.
But I agree, you don't need to trawl through heaps of out dated events. An archive is the way to go!