It goes against repairability, and sustainability which they're trying to promote.
I was very optimistic about this phone, but it looks like I'm going to have to go if the Google 5a
The headphone jack is a strange hill to die on when you get the chance to replace pretty much every important part. A well made dongle does not make a massive difference when you use headphones with a proper cable (I.e. not the flimsy thin headphone cables that rip or break within a few months of regular use).
It's not strange at all -- using headphones while charging is a daily situation for some