I have solid reasons why non-docked mode is the best, for me.
Sitting for hours just for coding is boring. I usually do some other tasks at once. My computer isn't very high-end but it has 32 GB of RAM, which makes it very suitable for multitasking. Also my monitor is 27", which can display 1920 x 1080 pixels.
As usual, now my Firefox is running at background playing some YouTube music vidoes. My Pale Moon is for doing research, currently it is displaying a forum post about an OpenGL topic (I marked red in the screenshot below). There has some code I want to integrated in to my source code (marked green in the screenshot below). Only novice programmers do copy/pasting code, not me. I am typing it manually into my source code.
Just for you information, I use 3 browsers, 4 graphics applications, 2 virtualization software, and frequently running 2 instances of Lazarus IDE at the same time. I know I am weird.
I really did install Anchor Docking in the past. Not impressed. I couldn't peek into the things behind as I did in the screenshot below. I couldn't arrange the forms layout easily. I have a big screen, I need to drag the forms frequently easily to where I want. I couldn't make a certain form Always-on-Top (Linux's feature, Windows doesn't have it).
I can understand many users especially beginners do not like the non-docking mode of Lazarus IDE. It can be messy, but if you know how to use Lazarus Desktop feature, problem solved. You can have several Desktops, for different tasks. You can switch between the layouts easily. And for Linux users, you have Always-on-Top feature, very useful.
If anyone does coding like how I do, using a big screen, hate copy/pasting code, understand how to use Lazarus Desktop feature, frequently use Always-on-Top and like multitasking, I believe s/he prefers non-docked IDE.
~ Forgot to mention: ~
If you want to use non-docked mode, you better enable:
Lazarus main menu > Tools > Options > Environment > Window > Show single button in TaskBar