The Senate would just continue to get nothing accomplished as the opposing party would just perform sit-in discussions about nothing for months on end. Then you would want to change the rules again to limit the amount of time debate could occur. So, it would end up requiring 41 votes to continue debating, unless the debating extended beyond 40 hours, and then you set an arbitrary method to end debate. Sounds great when you are in power and then you will regret it when you lose power, unless you stack the cards in your favor with the change in rules so that you never lose power again. The current system is the best we have for a reason and should stay that way.