The vast majority of web sites are crap. I'd really rather default disable javascript and opt-in if I decide I want to allow their code to run on my machine.
This. It's not really about tracking. Most of the websites embed tons of JS for no good reason, just because developers are lazy fashionistas and designers wouldn't be able to justify their pay if they didn't add tons of unneccessary bells and whistles.
There are web applications that need JavaScript, and I'm fine with that. There's lot of cool stuff JS could be used for, and it's not used - check out Bret Victor's explorable explanations. But instead doing something useful with this power, web designers and developers just use JS to make "shitty skeuomorphic bastardizations of what should be text communicating a fucking message" - as the quote from a very insightful article goes[0].
