I think it would be cool to be able to set up an exhaust system for the machines that you could funnel into primary trunks/chimneys.
This way you could make enclosed factory buildings and have them be several stories and actually have functioning smoke stakes that all the machines feed.
Right now none of the machines in my playthroughs are in buildings because I like to build as close to realistic as possible and it's nice to see the pollution that my progress brings lol.