One of the things that makes Lego so great is the ability to rebuild sets into something new and different. However, I know that sometimes TLG uses large pieces to lower costs and/or build complexity. Some examples:
It seems to me that some part choices are quite strange. For example, 7346 - Seaside House contains 2 1x2x2 bricks and 28 regular 1x2 bricks in medium blue. It doesn't seem like the double height bricks provide a much simpler or sturdier build, and the part is less reusable. I would have rather seen 1x2 bricks used throughout, especially since this is a Creator set, which focuses on being rebuildable.
I also found it strange that they chose to use 1x2x2 bricks in two places, but kept 1x1 bricks stacked 5+ high in others. It seems that if the goal is to create a sturdier model, replacing these stacks with 1x1x5 bricks would have been a good place to start.
So, I guess my question is: what goes into the decision of which specific parts to use in a production Lego model?