Tuidjy, I'm personally curious what you thought was boring about the demo and where your interest peaked when you revisited the game. Yes, this is something Larian would usually ask, but your response piqued my interest.
I believe these were a compromise. Many secrets are not nearly as obvious. If the keys were very well hidden as they are in the earliest quests they would drastically impede progress for players that are not used to unassisted problem solving.
Decisions don't mean much
Forking narratives are very time consuming to implement. If you ever read Choose Your Own Adventure series of gamebooks you quickly realize the amount of pages necessary to implement a relatively short story. Larian's use of framed stories to allow you to dig into smaller sub-stories through minor choices and quests is a great compromise for a smaller team.
