There are many, many reasons I continue to use L3 as my main Logos resource, just using L4 mostly for certain kinds of searches, its presentation of my Library, and occasionally for extended reading in a floating pane. One of the reasons I find L4 at times excruciatingly annoying is the disappearance of many features I use regularly, such as the Back and Forward buttons on windows.
As the picture below shows, L4 has such "buttons" but with one significant feature missing.

L3, as the picture below shows, has "down" buttons next to the Back and Forward buttons each of which displays approximately 10 "clicks" in that direction. This is an invaluable resource, allowing the ability to both see what is in both directions before I start clicking around trying to find the page I am looking for, and also allowing for quick bulk clicking to reduce the number of clicks necessary to get to resources I was using hours ago or even days ago. In L4...It's all just one big guess. Am I even clicking in the right direction? Who knows?

Since I don't use L4 all that much, I am sure I don't know all that it has under the hood, so maybe I'm overlooking this? I hope so...because otherwise it just confirms to me that L4 is inferior to L3 in many extremely important ways. I wish I didn't feel that way...but I do, and I don't see that ever changing.