It’s unintuitive for me to click and hold on the toolbar icons to open the tool submenus. I don’t think that feature should go away, but I’d like to be able to double-click the icons as well. It was what I immediately tried to do from my experience with other programs, but I was confused when it didn’t work and I didn’t even think to click and hold.
I think it’s up to ones personal preferences and to the operating system (or up to the OS’ desktop environment) one works. On Windows 10 you click and drag items to open subnenus, so - using Blender’s Toolbar I didn’t even noticed, that the drag action isn’t necessary. It just works for me. Double click isn’t so obvious then.
That’s why I think it should be a choice. I’m not familiar with clicking and dragging to open menus on Windows 10, since I’m used to double-clicking.
I just checked the Photoshop (maybe in newer versions it’s different) works only press and hold.
The double-clicking on some icons may perform an action, such as zoom to 100%.
Also in other programs, such as Affinity Photo, there is an opportunity to click directly on the small arrow to immediately open the sub-menu.
Double-click is used to rename or reset the value to default. I’ve never seen a double-click used to open a menu.
I still like double-clicking, but even being able to click the arrow to expand the submenu would be nice. I’m not super familiar with PhotoShop or Affinity Photo so I can’t use them as a frame of reference myself.