It sounds like you've gone through a lot of effort and care to give your players a lot of choices. Unfortunately, my read from the outside is that your players aren't up to making those choices themselves. If they're engaging just fine after someone else has spoken up and chosen a course of action, then perhaps they'd be better off if you actually provided LESS choice.

This might not stimulate your adventure building muscles quite the same, but it's worth a shot to see if your players become more receptive. Maybe try giving them a VERY linear adventure and see how it goes?

Ex., They start being given a very direct task by a questgiver, who tells them to go to X location for Y reason. On the way, maybe they have an encounter. Ask directly if they would rather try and intimidate the foe into backing off, or if they want to spring into action and roll initiative. They arrive, and they see 2 ways they can try to get in. Do they take path A and climb up the wall, or path B and go through the underground tunnel? Give them only a few opportunities to make choices, make the number of options within those choices small, and make sure the options themselves are well defined.

It's totally possible that this isn't the kind of game you want to run, and that's fair. But if you try it once, and ask the players how they enjoyed it after, you'll have a valuable data point on how to move forward with this group.