Agree to disagree, then. I'm OK with a new story
not being as formulaic as 99% of zombie-style stories, and that means it's OK to have the first wave of baddies
not be overwhelmingly dangerous. By appearing out of nowhere they were the 2nd threat that appeared (after the mist itself) and plot-wise served to increase the danger level a little more, which until then was "only" a nuisance+ (moderately irritating/corrosive). Then they turned out to be a bigger part of the worsening of the situation by actively turning people, accelerating the change/infection.
I think that's fine as a starter baddie, and I'm not sure why you want/expect more than that.

For me I am reading
this story, not wanting it to be more like
other stories, because...what would be the point? The devs have their story framed out and this is how they are telling it. Without having any idea where they are going it seems odd to say any part of the early plot is "too much this" or "not enough that,"
especially when it may turn out that BOs are a bigger problem than we thought quite organically (pun intended) as part of the story
we just haven't gotten to yet: