Why Decision Log is important for an Architect?
As an Architect during the life cycle of Product Development, key decisions will be made for some valid reasons. Often if these reasons are not documented in a Decision Log then down the lane it will be hard for anyone to understand why certain decisions are made at that time. I personally get challenged asking these type of questions typically when people leave the project and new people take the role and they would like to understand why certain decisions have been made and rationale behind them. Having a Decision Log and documenting the rationale will be really handy in these situations. As Simon Brown mentioned in his " Software Architecture for Developers " book keep them simple as it is mainly for technical audience.