While I agree the game is time bound by points per second, especially in upper leagues, I personally think this is a good idea.
My reasoning is that unless the game is desired to be a game of head to head administration, less time should be needed on administrative overhead. More time should be on strategy and battle.
While I agree it can be a difference maker to come prepared, It would reduce the amount of unimportant time wasted, and doesn’t remove the choice/strategy for which base is better to hit.
It could be they don’t display this for performance reasons, but I personally would like a better tool to compare players and teams rather than the slow process of pretending to attack, cancelling and having to reload the team page again.
If done right it might even reduce the load on the game which could save pg money as thousands of people will reduce their number of slow queries drastically in number.
If somehow the diamond folks felt they really wanted to keep things how they are, id recommend it as more of a training wheel type change for leagues under a certain level. (Although i find it hard to believe there are competitive teams in diamond who don’t bother to prepare still)