I am in that age group. I need my glasses - and I need things to be bigger. Everything in the Designer looks a bit too small. Especially in the style panel, that I use 90% of the time.
Much like Photoshop, allowing users to decide which zoom factor to have in the Designer interface would be very helpful. That way we can still produce our designs at the browser's standard zoom setting.
You could add this function in a button right next to the Preview Toggle.
Bigger interface for larger monitors yes.
Same issue. A zoom feature would be much appreciated. Some small tweaks, e.g. when setting the padding, the number could be blown up a bit (then go back to small), and a general zoom setting for the screen. I'm working on a 4K monitor, and I feel like Webflow's current interface is only optimised for 15 inch laptops (Webflow is just about able to function on a 13 inch, but that's ok, I manage). For those of us who're are on iMacs and other larger screens, it'd be nice to have a zoom-in function.