I think the problem you will find is Space!!!
Meaning if you have 500 people waiting in an area the size of a tennis court it will look and feel longer than if you are are all in say the size of a football pitch. That is the reason the barriers are there. Not ideal I know but if you have two flights down with no barriers they will be all the way up the stairs and out of the doors.
Say you wait 10 mins for immagration to let you through the time you wait for your baggage appears less. Often you can walk from stand 4 clear immagration and have your baggage waiting for you!