If the buttons are small, they are harder to click. It's also harder to understand what they do, which is important when they have icons that are just cryptic monochrome squiggles.
What's the merit in making the buttons unobtrusive? What are you going to do with all those saved pixels? There is no pixel shortage on desktop! That's a mobile design consideration.
When the browser is covering a sixth of my screen it's already uncomfortably large. There is no reason to save hundreds of pixels when there are literally millions to spare.
Given this line of thought, why doesn't Firefox put every single icon from the menu on the toolbar. Since there is so much space. My argument is that since those buttons are rarely used, they should be unobtrusive.
Your toolbar is a nightmare for people that may have some eyesight problems or are not expert FPS shooters in the latest triple A game and miss some mouse dexterity.
What I'm trying to say is that a large surface is good for muscle memory. And I have a lot of pixels to play with, 4k screens are cheap. Of-course programs have to scale between small and (very) big screens, but making everything very small by default is not the way to go.
>My argument is that since those buttons are rarely used, they should be unobtrusive.
Why the half measure? If they are rarely used remove them. If they are used enough to leave them on the UI make them big enough and labeled well enough that I don't need a decoder ring and magnifying glass. Making them small and unintelligible is probably the best way to make them rarely used.
Firefox Account (not an extension - I really should hide it)
uBlockOrigin
Honey (basically coupons)
PushBullet (I use this occasionally to move links or images between the PC and iPhone. Should probably get rid of it since Firefox now supports functionality natively).
What's the merit in making the buttons unobtrusive? What are you going to do with all those saved pixels? There is no pixel shortage on desktop! That's a mobile design consideration.
When the browser is covering a sixth of my screen it's already uncomfortably large. There is no reason to save hundreds of pixels when there are literally millions to spare.