Dev tools of a browser are not what a power user focused browser would need. Think more about being able change keyboard shortcuts. Being able to execute small custom scripts that do stuff with tabs, windows, and pages. Yes I know browser plugins and bookmarklets exist.

But why do bookmarklets run with the security context of the currently opened page? I have one self-written bookmarklet to capture the page title and url into emacs for storing it there. Firefox asks me every time I click on that bookmarklet on a new origin (domain, protocol tuple) whether I want to allow that. With no option to avoid that. I have written this piece of code myself I want to use it to enhance my workflow. There is no need to treat it like any javascript hosted on a CDN, or on a Facebook server.