[gioele]

> seems silly to have wasting space on the hard drives of millions of users.

I'd be more worried about memory consumption, wasted CPU cycles, lost opportunities to let the CPU sleep, the cost of running CI tests...

I am also worried about the increase in the attack surface exposed to random pages downloaded from the Web.

[mikeratcliffe]

All Firefox Developer Tools are lazy loading so they do not use extra memory unless you open them.

Also, having the tools built in means that they are tested every time any core Firefox code is changed leading to a much more stable environment.