Peter - I agree with you but I rather think the notso regular ceilidh goer or beginner will not get as much from the information. AND there is always the caller's version which the golden rule states will differ from your pre-concieved notion and by the time to dance you haven't been paying attention because you know it anway (NOT me I hasten to (cough) add (cough)).
Then there is the caller who misses-out bits because he is going from memory and you still don't know, until the dance is under way, if this is a shortened version or the old favourite and half the set is about to stand around looking perplexed with the new figure that I am doing because I heard the anticipated late call.
Knowing what the dance is called is a 50% proposition but better than 0%.
Announcing the type (& size) of set should be called amny times according to the concensus of contributors to the list - have a look and see - it is growing.