Greek Civilization (Read the details)?

The Mycenaeans were Greeks. They conquered the Minoans and adopted much of their culture, including:

-an early script for writing Greek (called Linear B, which is separate from the later Greek alphabet).

-major influences in art and architecture (you just have to look at some pottery or wall paintings to see what I mean)

There are other things I could point to; this is just to get you started. The question "were they necessary steps" is kind of redundant. If the Greeks hadn't gone through this phase, then by definition, their history would have unfolded differently and they would not be the same Greeks we know today.