Gday. As tittle said, this is what I think a lot of people want really bad, but just didn't ask. Just before both tower and raid events, the forums get chaotic because of team changes, requests canceled, people dropped out, etc. So this way we will have enough time to think it trough, set up the teams, and get this game to the next level.
Even elite teams often get messed up because of such a short time frame, due to the fact that over 95% of FF players aren't going all out on all events. They make promises, see the crap rewards, then say "meh, screw that, I dont care I aint playing". On the other hand, some dont plan on going high, but if they like the rewards, they decide that their casual allies aren't going to lift enough, and they go searching for others, all in a 2-3 hours timeframe. Wont even talk about the one in charge that has to organize 2-3 teams.
There are also people that are at work, asleep, or generally not on the phone when the JSON is released. This hits them hardest, and makes a complete mess of what they thought they would enjoy.
So, by giving us enough time to figure it all out, and get our game faces on, everything runs more smoothly, and that means more rewards for us, more profit for you.