Heh, what can I say, nerding out about UI design is definitely part of my general dysfunction.

But yeah, if you're already in a 19:10 display you generally won't want the sidebar as much because you already have a naturally taller display, so your workspace is shaped the same as mine when you use horizontal and I use vertical. It's probably more a problem of proportions that sizes.

Which, hey, is why being able to have a vertical and horizontal tabs option is good. We're in a world where browsers need to fit not just horizontal and vertical displays on PCs and phones, but a whole bunch of screen aspect ratios.