Yep there would always be the temptation to say "well I need just one cookie" or "well I need just this bit of javascript" Gemini doesn't give you those options.
It’s also make the protocol considerably easier. I read it in two small settings. It’s surprisingly digest and make you want to start implementing a server or a client for it.
I think it's only a matter of time before Gemini does that. The moment it's actually used by people who aren't interested in the underlying tech, someone will fork the browser and include either video support or scripting of some kind. Or they'll say, maybe it should display PDFs too - and that will bring the JS engine in as well.