[2020] Interesting bot picks...Pack 2 Pick 4, the rare and uncommons are ALL unpicked. Wonder what the commons were...

This isn't *universally* true - there are situations in which the automated drafters will take cards outside their colors. But that can easily not come up by pick 4 in a pack.

In general, though, you are correct to point out that a multicolor card is less likely to fit any given drafter's colors and therefore more likely to be passed (whether they're automated or human).