The main reason they've never changed it is exactly the same reasons that pointy football keeps trying to reduce game times - TV. With the current system, any broadcaster knows that 95% of matches *will* last about 110 minutes from kickoff to final whistle, with no more than at the absolute most, five minutes of variance. Add five minutes of intro and five go-home on and that fits very neatly into two hours for a bare-bones presentation. (The real benefit of this is that it makes it incredibly easy to sell to overseas broadcasters as a minority-interest thing that they can do on the cheap, and now your foot's in the door of another foreign market.) Make it twenty of each and you have a basic studio presentation that'll fit into two and a half hours. NFL broadcasters would surely kill to know with absolute certainty that 95% of games would be between 2hr40 and 2hr45 minutes, no?