[andix]

I don’t know. Not an UX expert. But I think the key is the right amount of information. Too much and not enough is both equally bad.

But we have much bigger screens than many years ago when thunderbird was initially designed.

Laptop screens stayed mostly the same sizes, so it makes sense to adjust density to the device type you are using or the window size. This is already done for smartphones, mobile websites usually have much smaller paddings. Same is usually done for iOS vs iPad apps.