Yea, I agree. It's really disappoitning. The contrast just isnt sharp enough. I don't know what is with designers and loving low contrast type, but it's unfortunate. (Heck, even the search box on this site has way too little contrast between the white background and 15% grey text.) I wanted to replace illustrator, but until there is a light UI with enough contrast to actally read tab names this app just isn't going to work.
All the best luck to the Affinity team, but the dark UI is a non-starter for my professional work. I am only 35 and I can't handle the squinting required (or zooming on my 13inch Macbook Pro). Here is hoping this is feature is at the top of the priority list.