180 is a convenient length for small jobs. Not just for the actual cutting part, but also all the handling - walking around with it, setting it down, washing and drying, etc. Plus a 180 is less length to sharpen when you hit the stones, and again with all the handling conveniences of a smaller knife. I’m not going to slice a brisket or cut a butternut squash with one, but a single onion, some garlic and tomatoes for tomato vodka sauce? Sure thing.
I use a 180 gyuto and bunka interchangeably. The height of the bunka is nice for the guiding knuckle, but not a huge deal either way. My wife has a 165 santoku that I’ll grab to cut oranges, but otherwise is really too small for me to consider cooking with.