Absolutely this. I tend to put my browser on a monitor that's been rotated vertically so I have tonnes of vertical screen real estate. I have a bunch of common tabs pinned, and the current design doesn't let me take advantage of this at all.
This was my main issue with the vertical tabs. I keep 6 tabs pinned at all times and I never want to have to scroll for them. Ideally, I never want to scroll for any number of pinned tabs unless my total number of tabs requires scrolling.
My solution locally was to modify userChrome.css, and add the following:
/* Vertical tabs allow all pinned tabs to show. */
#vertical-pinned-tabs-container {
max-height: none !important;
}
What I personally want is for all pinned tabs to always be visible without manually resizing it after adding additional pinned tabs. I think if it's at its maximum height, it should automatically expand when you add another pinned tab. If you have a height set (resized smaller than max) then it should maintain that height.
To have it always be the max height, you can use this userChrome.css style. Do note that this will prevent you from having the ability to resize.
#pinned-tabs-container {
height: auto !important;
}