While I have found a couple of extensions that adjust font size specifically, it would be nice to be able to increase or decrease the font size independent of scaling the UI and based upon client preferences. Some of my players, and myself, have a difficult time seeing the text in the chat window. Scaling the UI crowds the screen making the interface a little difficult to work with. Most of my players are on laptops and screen space comes at a premium.
I would imagine folks who have 13.5 inch laptop screens find that scaling the UI up makes it very difficult to interact with the environment. Thus increasing the font independent would help everyone.