i c your point the majour thing is relaying the info that luke blew it up to vader. and that could be done very quickly. and for those that are watching it in order it would increase the drama and give purpose to some of the things that became redundant after the PT, just cause the audence knows something it doesnt mean that the characters, magically find out. its part of drama, seeing the reaction when you know something is the case when they dont, then seeing them find out.