AbigailII: One big disadvantage of your proposal is that it is too complicated and difficult to understand to somebody who just comes to play Backgammon or Ludo (there are people who NOW have problems with understanding to it, so what would it be after making it more tricky).
Moreover, many people dont want to bother about the game time and just use the automatic settings when sending an invitation. In your system, they would have to set pool: 0/0, move (any), bonus: 0 (or, if it would be automatically set, at least think about it if it doesnt mean something they dont want)

By the way, I dont agree with number 6. Imagine, that you go to work every day (it happens sometimes :)) ) and you have no possibility to play BK when at work. So, you have time to play only in the evening. And you have some games which need to be played today (or they will timeout tomorrow during the day). Now, if the server is unavailable during all the evening, you can lose all of them, this is why you need 24 hours.