Well you already have the half way line as an offside barrier. Do you want to get rid of that as well? Teams don't leave 3 or 4 players there and hoof it. If that line was nearer the goal the play would become more open.
I find it annoying that a team can score in the 89th minute, celebrate for 3 minutes and find the ref adds on 4 minutes stoppage time. Another alternative would be to play 60 minutes - ball in play, which would involve an independent time keeper.
Some do....
The only reason all players come back to the half way line is because they have to, they wouldnt if they werent offside.
Having the halfway line as a barrier at least condenses the play and makes passing and movement important, having too much space takes a lot away out of the game.