Totally fair point. In both cases, I think design follows the Rule of Least Surprise to create a consistent experience for users. It's about business aims, too.

Totally fair point. In both cases, I think design follows the Rule of Least Surprise to create a consistent experience for users. It's about business aims, too. WhatsApp went after native messaging, so it made sense for them to make the transition as seamless as possible. Google Drive applications are operating on a completely different scale. At the same time... Google Drive applications looked very familiar to people coming from the MS Office world. If you're trying to replace a competitor, mimicry isn't a bad place to start.