I agree that the real issue is dead worlds. So, what is the root cause of that?
I don't think its the attack alarm, or night bonus, or the lack of night bonus. Night bonus just affects when you plan you attacks to land. Not when they can be sent. I can still ring someones attack alarm (assuming it's working at the moment) by launching my attacks late at night to land after the night bonus window. I sure someone will correct me on this, but aren't the US servers a little different from some of the other countries in that they inherently span multiple time zones, and seem to attract players from around the world, making the night bonus concept a bit more challenging.
I would put 4 alternate theories out there for the dead worlds and lack of new players:
1) Frequent events - the events disrupt the growth of a world. This is especially true with experienced players that drop non-trivial gold to get the awards they want. I would guess that new players spend very little while they are getting up to speed on the game. Remedy: exclude new worlds from events for the first 3-6 months to actually let the world get started and have people actually need to rely on strategy and ability instead of relying on event boosts.
2) Gold - need more be said? If the perception by new players is that the only way to succeed in the game is to spend a lot of money, they will find another game. The perception may, or may not be real, but with gold in events, and the change from halving the completion time to instant complete means that early in a world, gold can be king. It doesn't make a bad player great, but does give them an advantage. Instant complete on buildings means a wall can go back up in no time, and the units can be instantly completed to reinforce a city. Remedy: Change these back to only being able to half the remaining time, or put a cap on the number of instant completes a player has each day (with no way to buy more).
3) Impediments to small player growth - I've written else where on the down side of the BP farming villages, and how they are a drag on growth for smaller players. This is especially true if a player is in a relatively quiet part of a world, or aren't part of an alliance yet. Remedy: add resource based farm villages back as an option for smaller players.
4) All of us - Those of us that have played for a while tend to fall into playing with the same teams from world to world, and with the low alliance limits, tend to stick with the players we know. There's no incentive to 'waste' an alliance spot on an unknown/new player when you can take some one you've played with before, or can look up a history on. Remedy: Add 10-20% newbie bonus cap on alliance size.
Just some of my thoughts on it.